Difference between two values of a dimension

[curiousfellow]

In my pivot table I have two dimensions as a columnheader.

First dimension is year, second is a calculated dimension.

I want to calculate the difference between two years as a percentage.

$(vmaxyear) is the most recent yearvalue (not calander-year)

So I have an expression like this :

for current year :  count({<year=('=$(vmaxyear)')>}employees)

for previous year  count({<year=('=$(vmaxyear)-1')>}employees)

but that does not seem to work. Because the second dimension doesn't always has the same number of columns, I can not use something like before() or below()