-99.6% is the change from 990 to 4
Calculation steps:
[( 4 - 990 ) ÷ 990] x 100 = -99.6%
Formula
Percentage change = [(4 - 990) / 990] x 100
Subtract the new number by the original number
4 - 990 = -986
-986 ÷ 990 = -0.9959595959595959
-0.9959595959595959 x 100 = -99.6%