-2% is the change from 998 to 978
Calculation steps:
[( 978 - 998 ) ÷ 998] x 100 = -2%
Formula
Percentage change = [(978 - 998) / 998] x 100
Subtract the new number by the original number
978 - 998 = -20
-20 ÷ 998 = -0.02004008016032064
-0.02004008016032064 x 100 = -2%