Vb macro code to start from 100 ….

Vb macro code to start from 100 ….
In this coding, the average is starting from 200 (TT) and it is proceeding as 300, 400, 500, but I need to start from 100th value....

and also this code is working only with AI and AK COLUMN (which is inconvenient for me ) so please do changes in the code so that it can work in any of the columns if I double click on the cells, please do modify the code and give me.. Please do help me.. I think may be my question is not clear and so I’m attaching the excel file ALONG WITH THE CODE with this POST so that it will be very easy for you to understand my query… please find the attachment for your kind reference and perusal...
Please oblige and do the needful…

Thanks & Regards,
Dharani.