diff --git a/app/controllers/stats_controller.rb b/app/controllers/stats_controller.rb
index 65ac6739..405aafbd 100644
--- a/app/controllers/stats_controller.rb
+++ b/app/controllers/stats_controller.rb
@@ -41,10 +41,13 @@ class StatsController < ApplicationController
   end
 
   def interpolate_avg_for_current_month(set)
-    percent_of_month = Time.zone.now.day.to_f / Time.zone.now.end_of_month.day.to_f
     (set[0]*(1/percent_of_month) + set[1] + set[2]) / 3.0
   end
 
+  def percent_of_month
+    Time.zone.now.day / Time.zone.now.end_of_month.day.to_f
+  end
+
   def actions_done_last_years
     @page_title = t('stats.index_title')
     @chart = Stats::Chart.new('actions_done_lastyears_data', :height => 400, :width => 900)