-74.02% is the change from 639 to 166
Calculation steps:
[( 166 - 639 ) ÷ 639] x 100 = -74.02%
Formula
Percentage change = [(166 - 639) / 639] x 100
Subtract the new number by the original number
166 - 639 = -473
-473 ÷ 639 = -0.7402190923317684
-0.7402190923317684 x 100 = -74.02%