Help with %s in visual

Hi all,

Hope somebody can help with my query.

I have the below visual. The black bar shows how many cases are currently open, the red bar shows how many cases are overdue, and the percentage is % of open cases that are currently overdue. However, the % is not changing and is always staying as the same figure. Please see below visual attached:

The week of 15th Jan, the % should be 100, but instead is showing as the 76.19 which is the current and correct % for this weeks report. 

What should be happening is the line should be different based on each week at the bottom, but for some reason the number is staying the same for each week.

Any ideas or advice would be greatly appreciated.

Many thanks

DRJ