-4.77% is the change from 671 to 639
Calculation steps:
[( 639 - 671 ) ÷ 671] x 100 = -4.77%
Formula
Percentage change = [(639 - 671) / 671] x 100
Subtract the new number by the original number
639 - 671 = -32
-32 ÷ 671 = -0.04769001490312966
-0.04769001490312966 x 100 = -4.77%