62.78% is the change from 309 to 503
Calculation steps:
[( 503 - 309 ) ÷ 309] x 100 = 62.78%
Formula
Percentage change = [(503 - 309) / 309] x 100
Subtract the new number by the original number
503 - 309 = 194
194 ÷ 309 = 0.627831715210356
0.627831715210356 x 100 = 62.78%