-68.08% is the change from 639 to 204
Calculation steps:
[( 204 - 639 ) ÷ 639] x 100 = -68.08%
Formula
Percentage change = [(204 - 639) / 639] x 100
Subtract the new number by the original number
204 - 639 = -435
-435 ÷ 639 = -0.6807511737089202
-0.6807511737089202 x 100 = -68.08%