diff --git a/app/helpers/timeline_helper.rb b/app/helpers/timeline_helper.rb
index a1cc0d3..29859bc 100644
--- a/app/helpers/timeline_helper.rb
+++ b/app/helpers/timeline_helper.rb
@@ -29,21 +29,21 @@ module TimelineHelper
     max = max_days - started_days(member)
     distance > max ? max : distance
   end
+
+  # weekly occupany, hash containing weeks to number of volunteer mapping
   def weekly
     data = {}
-    week = 0
-    while( week < @weeks ) do
+    month_start = Date.today.at_beginning_of_month
+    ( 0 ... @weeks ).each do |week|
       data[ week ] = -1
-      start_week = Date.today.at_beginning_of_month + week.weeks
-      end_week = Date.today.at_beginning_of_month + (week + 1).weeks
+      end_week = month_start + week.weeks
       @members.each do |mem|
         next unless mem.arriving
         next unless mem.leaving
-        next if mem.arriving > start_week
-        next if mem.leaving < end_week
+        next if mem.leaving <= end_week
+        next if mem.arriving >= (end_week - 7.days)
         data[ week ] += 1
       end
-      week += 1
     end
     data
   end