-3.33% is the change from 661 to 639
Calculation steps:
[( 639 - 661 ) ÷ 661] x 100 = -3.33%
Formula
Percentage change = [(639 - 661) / 661] x 100
Subtract the new number by the original number
639 - 661 = -22
-22 ÷ 661 = -0.03328290468986384
-0.03328290468986384 x 100 = -3.33%