-9.7% is the change from 639 to 577
Calculation steps:
[( 577 - 639 ) ÷ 639] x 100 = -9.7%
Formula
Percentage change = [(577 - 639) / 639] x 100
Subtract the new number by the original number
577 - 639 = -62
-62 ÷ 639 = -0.09702660406885759
-0.09702660406885759 x 100 = -9.7%