SAP BO WEBi. Trend of Present + Past 7 Weeks

Hey Everyone,

                    I want to show Previous 8 Weeks Trend in a Column chart, and the weeks are in Input Control. Total 24 weeks.

                    If Week 1 is selected --> Trend 1st week data should appear in Column chart

                    If Week 2 is Selected--> Trend of 1st and 2nd week should appear in Column chart

                    If Week 3 is Selected--> Trend of 1st,2nd and 3rd weeks data should appear in Column chart

                    and soo on

                    But if 9th Week is selected --> Trend of 9th week and previous 7 week should appear

                    If 10th Week is Selected --> Trend Of 10th Week and previous 7 Week Should Appear

                    And so on

                    If 24th week is Selected--> Trend Of 24th Week  and Previous 7 Week should appear.

Please Get let me know the solution as soon as possible.

Thanking You,

Mohit Kurseja.