BADI in BPC for Forecasting

Hi,

My requirement is to read month wise data for 3 years from infocube and average out the sales data for that month for 3 years and put

the average value in current planning year for that specific month in another infocube.

Say,

Year    Month     Sales

2011   April         100

2012   April         110

2013   April         120

Average sales value should be put in month April for year 2014 and put this value in other infocube.

Which Badi can be used for this purpose in BPC and how can i use it?

Please help.