-98.48% is the change from 990 to 15
Calculation steps:
[( 15 - 990 ) ÷ 990] x 100 = -98.48%
Formula
Percentage change = [(15 - 990) / 990] x 100
Subtract the new number by the original number
15 - 990 = -975
-975 ÷ 990 = -0.9848484848484849
-0.9848484848484849 x 100 = -98.48%