-97.98% is the change from 990 to 20
Calculation steps:
[( 20 - 990 ) ÷ 990] x 100 = -97.98%
Formula
Percentage change = [(20 - 990) / 990] x 100
Subtract the new number by the original number
20 - 990 = -970
-970 ÷ 990 = -0.9797979797979798
-0.9797979797979798 x 100 = -97.98%