How to sum last year.

[#1]

I select  current year(don't care Month) from list box for sum product but i don't know scrip to sum product last year.

Ex

Item	Sum all 2014	Sum all 2013
101	3000	?
102	4000	?

anyone have a idea?

[#2 · Accepted solution]

sum({<Year={$(=Max(Year)-1)}>} <your field>)

[#3]

please help.If i want to sum all last year.what code look like.