really faster stats by precomputing some of them

db/migrate/20201002124154_create_stats.rb

@@ -0,0 +1,18 @@
+class CreateStats < ActiveRecord::Migration[6.0]
+  def change
+    create_table :stats do |t|
+      t.bigint :dossiers_not_brouillon, default: 0
+      t.bigint :dossiers_brouillon, default: 0
+      t.bigint :dossiers_en_construction, default: 0
+      t.bigint :dossiers_en_instruction, default: 0
+      t.bigint :dossiers_termines, default: 0
+      t.bigint :dossiers_depose_avant_30_jours, default: 0
+      t.bigint :dossiers_deposes_entre_60_et_30_jours, default: 0
+
+      t.jsonb :dossiers_cumulative, null: false, default: '{}'
+      t.jsonb :dossiers_in_the_last_4_months, null: false, default: '{}'
+
+      t.timestamps
+    end
+  end
+end