Last year contribution (L) = $ 3,000
This year contribution (T) = $ 1,000
Hence, percentage decrease = [tex] \frac{T - L}{L} * 100 = \frac{1000-3000}{1000} *100 = \frac{-2000}{1000}*100 = -2*100 [/tex] = - 200 %
The negative sign shows the decrease in the percentage.
Hence, the percentage decrease was by 200 %.