-0.1% is the change from 990 to 989
Calculation steps:
[( 989 - 990 ) ÷ 990] x 100 = -0.1%
Formula
Percentage change = [(989 - 990) / 990] x 100
Subtract the new number by the original number
989 - 990 = -1
-1 ÷ 990 = -0.00101010101010101
-0.00101010101010101 x 100 = -0.1%