Compare this year sales to last year

[#1]

hi,

how to get and compare particular two years sales of customers.

how to add a field which contains the past year and present year netsales.

[#2]

Use Set Analysis someting like for this year

Sum({1 <Year=Year(today())>},Sales)

and for last year

Sum({1} <Year = Year(today())-1},Sales)