I have the following table:

01-01-2012            10                  ACTUAL

01-01-2012            12                  BUDGET

01-04-2012            11                  BUDGET

I need to calculate:

BUDGET (as of 01-04-2012) = 23 (12+11)

ACTUAL (as of 01-04-2012) = 21 (10+11)

and chart it (see attached image)

BUDGET data is already in table

ACTUAL data is added daily

Can you give me any idea.. should I create a new column formula? But then how do I chart the comparison? What formula should I use?