-3.62% is the change from 663 to 639
Calculation steps:
[( 639 - 663 ) ÷ 663] x 100 = -3.62%
Formula
Percentage change = [(639 - 663) / 663] x 100
Subtract the new number by the original number
639 - 663 = -24
-24 ÷ 663 = -0.03619909502262444
-0.03619909502262444 x 100 = -3.62%