calculate % in a cumulative tabel

[chriscools]

Hello,

i have a tabel with 4 columns:

month

invoiced year 2010

invoiced year 2011

% (2011 / 2010 )

i made a duplicate of the tabel to have a view on the accumulated amounts.

i checked the option "full accumulation" on the expression tab for invoiced year 2010 and 2011.

but i also want to compare in % the accumulated totals, but if i also check the "full accumulation" for the % column it is not correct.

and if i leave it to "no accumulation" it calculates the % as if the other columns weren't accumulated either...

anybody knows how to do it?

grtz

chris