How to draw cumulative line graph over the stacked bar chart?(SSRS)

Hello, 

I need your help to draw a cumulative line graph over this bar chart. 

I need your help to draw a cumulative line graph over this bar chart in SSRS.

The dimension (Category Group) is "Hour" in this case. and expression is sum of two distinct values like 'Y' and 'N' in Activity column(Series Groups). The sum(Activity=Y) in green color and sum(Activity='N') in Red color.

I require to draw a cumulative line graph in this same chart, that should give the result of cumulative Sum(Activity) for each hour?? I mean sum of (Y+N) for each hour and that should be cumulative over the hour.

I mean sum of (Y+N) for each hour and that should be cumulative over the hour.

SSRS Version details:

Microsoft SQL Server Reporting Services Designers 
Version 10.50.1600.1

--Siva