Need help in the current year and previous year expression

[#1]

Hello Experts,

The sales of the year 2013 is 3371 but when i select the 2014 the actual sales of 2013 is reduced to 2011, how do i display the value correctly in the chart.

I have attached a document with my query.

Thanks in advance.

[MK_QSL]

=SUM({<SalesYear = {'$(=Max(SalesYear)-1)'}>}Sales)