4.23% is the change from 639 to 666
Calculation steps:
[( 666 - 639 ) ÷ 639] x 100 = 4.23%
Formula
Percentage change = [(666 - 639) / 639] x 100
Subtract the new number by the original number
666 - 639 = 27
27 ÷ 639 = 0.04225352112676056
0.04225352112676056 x 100 = 4.23%