3.23% is the change from 619 to 639
Calculation steps:
[( 639 - 619 ) ÷ 619] x 100 = 3.23%
Formula
Percentage change = [(639 - 619) / 619] x 100
Subtract the new number by the original number
639 - 619 = 20
20 ÷ 619 = 0.03231017770597738
0.03231017770597738 x 100 = 3.23%