ROE = E1/B0 (E1 is found in the IS end of year 2016 for example, B0 is in the BS end of year 2015 )
Or
ROE = E0/B0 (E0 is found in the IS end of year 2016 for example, B0 is in the BS end of year 2016 )
I suppose we want to calculate the ROE of year 2016.