diff --git a/app/controllers/stats_controller.rb b/app/controllers/stats_controller.rb
index 3d4e9e66d..1202df9c8 100644
--- a/app/controllers/stats_controller.rb
+++ b/app/controllers/stats_controller.rb
@@ -27,8 +27,8 @@ class StatsController < ApplicationController
       "Terminé" => stat.dossiers_termines
     }
 
-    @procedures_cumulative = cumulative_hash(procedures, :published_at)
-    @procedures_in_the_last_4_months = last_four_months_hash(procedures, :published_at)
+    @procedures_cumulative = cumulative_month_serie(procedures, :published_at)
+    @procedures_in_the_last_4_months = last_four_months_serie(procedures, :published_at)
 
     @dossiers_cumulative = stat.dossiers_cumulative
     @dossiers_in_the_last_4_months = stat.dossiers_in_the_last_4_months
@@ -136,27 +136,18 @@ class StatsController < ApplicationController
     end
   end
 
-  def last_four_months_hash(association, date_attribute)
-    min_date = 3.months.ago.beginning_of_month.to_date
-
+  def last_four_months_serie(association, date_attribute)
     association
-      .where(date_attribute => min_date..max_date)
-      .group("DATE_TRUNC('month', #{date_attribute}::TIMESTAMPTZ AT TIME ZONE '#{Time.zone.formatted_offset}'::INTERVAL)")
+      .group_by_month(date_attribute, last: 4, current: super_admin_signed_in?)
       .count
-      .to_a
-      .sort_by { |a| a[0] }
-      .map { |e| [I18n.l(e.first, format: "%B %Y"), e.last] }
+      .transform_keys { |date| l(date, format: "%B %Y") }
   end
 
-  def cumulative_hash(association, date_attribute)
+  def cumulative_month_serie(association, date_attribute)
     sum = 0
     association
-      .where("#{date_attribute} < ?", max_date)
-      .group("DATE_TRUNC('month', #{date_attribute}::TIMESTAMPTZ AT TIME ZONE '#{Time.zone.formatted_offset}'::INTERVAL)")
+      .group_by_month(date_attribute, current: super_admin_signed_in?)
       .count
-      .to_a
-      .sort_by { |a| a[0] }
-      .map { |x, y| { x => (sum += y) } }
-      .reduce({}, :merge)
+      .transform_values { |count| sum += count }
   end
 end
diff --git a/app/models/stat.rb b/app/models/stat.rb
index 7e2068e3e..ce0109c5b 100644
--- a/app/models/stat.rb
+++ b/app/models/stat.rb
@@ -30,11 +30,11 @@ class Stat < ApplicationRecord
         dossiers_deposes_entre_60_et_30_jours: states['dossiers_deposes_entre_60_et_30_jours'],
         dossiers_not_brouillon: states['not_brouillon'],
         dossiers_termines: states['termines'],
-        dossiers_cumulative: cumulative_hash([
+        dossiers_cumulative: cumulative_month_serie([
           [Dossier.state_not_brouillon, :depose_at],
           [DeletedDossier.where.not(state: :brouillon), :deleted_at]
         ]),
-        dossiers_in_the_last_4_months: last_four_months_hash([
+        dossiers_in_the_last_4_months: last_four_months_serie([
           [Dossier.state_not_brouillon, :depose_at],
           [DeletedDossier.where.not(state: :brouillon), :deleted_at]
         ]),
@@ -75,39 +75,33 @@ class Stat < ApplicationRecord
       )
     end
 
-    def last_four_months_hash(associations_with_date_attribute)
-      min_date = 3.months.ago.beginning_of_month
+    def last_four_months_serie(associations_with_date_attribute)
       timeseries = associations_with_date_attribute.map do |association, date_attribute|
-        association
-          .where(date_attribute => min_date..max_date)
-          .group("DATE_TRUNC('month', #{date_attribute}::TIMESTAMPTZ AT TIME ZONE '#{Time.zone.formatted_offset}'::INTERVAL)")
-          .count
+        association.group_by_month(date_attribute, last: 4, current: false).count
       end
 
-      sum_hashes(*timeseries)
-        .to_a
-        .sort_by { |a| a[0] }
-        .map { |e| [I18n.l(e.first, format: "%B %Y"), e.last] }
+      month_serie(sum_hashes(*timeseries))
     end
 
-    def cumulative_hash(associations_with_date_attribute)
+    def month_serie(date_serie)
+      date_serie.keys.sort.each_with_object({}) { |date, h| h[I18n.l(date, format: "%B %Y")] = date_serie[date] }
+    end
+
+    def cumulative_month_serie(associations_with_date_attribute)
       timeseries = associations_with_date_attribute.map do |association, date_attribute|
-        association
-          .where("#{date_attribute} < ?", max_date)
-          .group("DATE_TRUNC('month', #{date_attribute}::TIMESTAMPTZ AT TIME ZONE '#{Time.zone.formatted_offset}'::INTERVAL)")
-          .count
+        association.group_by_month(date_attribute, current: false).count
       end
 
+      cumulative_serie(sum_hashes(*timeseries))
+    end
+
+    def cumulative_serie(sums)
       sum = 0
-      sum_hashes(*timeseries)
-        .to_a
-        .sort_by { |a| a[0] }
-        .map { |x, y| { x => (sum += y) } }
-        .reduce({}, :merge)
+      sums.keys.sort.index_with { |date| sum += sums[date] }
     end
 
     def sum_hashes(*hashes)
-      {}.merge(*hashes) { |_k, hash_one_value, hash_two_value| hash_one_value + hash_two_value }
+      {}.merge(*hashes) { |_k, v1, v2| v1 + v2 }
     end
 
     def max_date
diff --git a/spec/controllers/stats_controller_spec.rb b/spec/controllers/stats_controller_spec.rb
index bb6c11914..4e9ae2e17 100644
--- a/spec/controllers/stats_controller_spec.rb
+++ b/spec/controllers/stats_controller_spec.rb
@@ -14,13 +14,15 @@ describe StatsController, type: :controller do
 
       let(:association) { Procedure.all }
 
-      subject { @controller.send(:last_four_months_hash, association, :updated_at) }
+      subject { @controller.send(:last_four_months_serie, association, :updated_at) }
 
       it do
-        expect(subject).to match_array([
-          [I18n.l(62.days.ago.beginning_of_month, format: "%B %Y"), 2],
-          [I18n.l(31.days.ago.beginning_of_month, format: "%B %Y"), 1]
-        ])
+        expect(subject).to eq({
+          4.months.ago => 0,
+          3.months.ago => 0,
+          62.days.ago => 2,
+          31.days.ago => 1
+        }.transform_keys { |date| I18n.l(date, format: '%B %Y') })
       end
     end
 
@@ -38,13 +40,15 @@ describe StatsController, type: :controller do
 
       let (:association) { Procedure.all }
 
-      subject { @controller.send(:last_four_months_hash, association, :updated_at) }
+      subject { @controller.send(:last_four_months_serie, association, :updated_at) }
 
       it do
-        expect(subject).to eq([
-          [I18n.l(45.days.ago.beginning_of_month, format: "%B %Y"), 1],
-          [I18n.l(1.day.ago.beginning_of_month, format: "%B %Y"), 2]
-        ])
+        expect(subject).to eq({
+          3.months.ago => 0,
+          45.days.ago => 1,
+          1.month.ago => 0,
+          1.day.ago => 2
+        }.transform_keys { |date| I18n.l(date, format: '%B %Y') })
       end
     end
   end
@@ -66,13 +70,13 @@ describe StatsController, type: :controller do
     context "while a super admin is logged in" do
       before { allow(@controller).to receive(:super_admin_signed_in?).and_return(true) }
 
-      subject { @controller.send(:cumulative_hash, association, :updated_at) }
+      subject { @controller.send(:cumulative_month_serie, association, :updated_at) }
 
       it do
         expect(subject).to eq({
-          Time.utc(2016, 8, 1) => 2,
-          Time.utc(2016, 9, 1) => 4,
-          Time.utc(2016, 10, 1) => 5
+          Date.new(2016, 8, 1) => 2,
+          Date.new(2016, 9, 1) => 4,
+          Date.new(2016, 10, 1) => 5
         })
       end
     end
@@ -80,12 +84,12 @@ describe StatsController, type: :controller do
     context "while a super admin is not logged in" do
       before { allow(@controller).to receive(:super_admin_signed_in?).and_return(false) }
 
-      subject { @controller.send(:cumulative_hash, association, :updated_at) }
+      subject { @controller.send(:cumulative_month_serie, association, :updated_at) }
 
       it do
         expect(subject).to eq({
-          Time.utc(2016, 8, 1) => 2,
-          Time.utc(2016, 9, 1) => 4
+          Date.new(2016, 8, 1) => 2,
+          Date.new(2016, 9, 1) => 4
         })
       end
     end
diff --git a/spec/models/stat_spec.rb b/spec/models/stat_spec.rb
index 518cf04bf..e9fc2edc2 100644
--- a/spec/models/stat_spec.rb
+++ b/spec/models/stat_spec.rb
@@ -57,24 +57,24 @@ describe Stat do
         create(:dossier, state: :en_construction, depose_at: i.months.ago)
         create(:deleted_dossier, dossier_id: i + 100, state: :en_construction, deleted_at: i.month.ago)
       end
-      rs = Stat.send(:cumulative_hash, [
+      rs = Stat.send(:cumulative_month_serie, [
         [Dossier.state_not_brouillon, :depose_at],
         [DeletedDossier.where.not(state: :brouillon), :deleted_at]
       ])
       expect(rs).to eq({
-        12.months.ago.utc.beginning_of_month => 2,
-       11.months.ago.utc.beginning_of_month => 4,
-       10.months.ago.utc.beginning_of_month => 6,
-       9.months.ago.utc.beginning_of_month => 8,
-       8.months.ago.utc.beginning_of_month => 10,
-       7.months.ago.utc.beginning_of_month => 12,
-       6.months.ago.utc.beginning_of_month => 14,
-       5.months.ago.utc.beginning_of_month => 16,
-       4.months.ago.utc.beginning_of_month => 18,
-       3.months.ago.utc.beginning_of_month => 20,
-       2.months.ago.utc.beginning_of_month => 22,
-       1.month.ago.utc.beginning_of_month => 24
-      })
+        12 => 2,
+        11 => 4,
+        10 => 6,
+        9 => 8,
+        8 => 10,
+        7 => 12,
+        6 => 14,
+        5 => 16,
+        4 => 18,
+        3 => 20,
+        2 => 22,
+        1 => 24
+      }.transform_keys { |i| i.months.ago.beginning_of_month.to_date })
     end
   end
 
@@ -85,15 +85,16 @@ describe Stat do
           create(:dossier, state: :en_construction, depose_at: i.months.ago)
           create(:deleted_dossier, dossier_id: i + 100, state: :en_construction, deleted_at: i.month.ago)
         end
-        rs = Stat.send(:last_four_months_hash, [
+        rs = Stat.send(:last_four_months_serie, [
           [Dossier.state_not_brouillon, :depose_at],
           [DeletedDossier.where.not(state: :brouillon), :deleted_at]
         ])
-        expect(rs).to eq([
-          ["août 2021", 2],
-          ["septembre 2021", 2],
-          ["octobre 2021", 2]
-        ])
+        expect(rs).to eq({
+          "juillet 2021" => 2,
+          "août 2021" => 2,
+          "septembre 2021" => 2,
+          "octobre 2021" => 2
+        })
       end
     end
   end