How to calculate total sum with the month value

Hello Gurus,

I am facing an issue in my current project i need to find out the quantity percentage in webi based on quantity.

Pls see the below table how my data is Exist in webi(Cross tab report).

Vendor name           jan       feb      mar       apr     may    jun    jul

AAAAa                   100       200    300       400     500    600   100

BBBBB                  110       210     310      410     510    610    110

Total                      210       410    610       810     1110   1210  210

Now my requirement is to calculate Percentage,here the scenario is i need to calculate Jan total with Jan(Single value) i.e. Jan total is 210 and jan month value is 100

100/210 i need to calculate in this manner .

What is the logic i need to write please suggest it is very urgent.

Any help would be appreciate.

Regards,

Mahesh