data formating results in 1905

I have two fields employees and Year. I am using this formula to calculate growth rate.

Growth % = divide (sum(Data[EMPLOYEES]) - calculate(sum(Data[EMPLOYEES]),SAMEPERIODLASTYEAR(Data[YEAR])), calculate(sum(Data[EMPLOYEES]),SAMEPERIODLASTYEAR(Data[YEAR])))

I am using sum because i have other fields which slices the employment data.

This gives error because Year is not date field. In "Modeling" tab, if i set the format to date then all the values become 1905. I understand its converting year 2013 to number which excel understands but is there is a easier way to fix this? 

I assume there has to be easier way to convert year values to date that PBI can use for calculations like this.