-97% is the change from 666 to 20
Calculation steps:
[( 20 - 666 ) ÷ 666] x 100 = -97%
Formula
Percentage change = [(20 - 666) / 666] x 100
Subtract the new number by the original number
20 - 666 = -646
-646 ÷ 666 = -0.96996996996997
-0.96996996996997 x 100 = -97%