6.47% is the change from 309 to 329
Calculation steps:
[( 329 - 309 ) ÷ 309] x 100 = 6.47%
Formula
Percentage change = [(329 - 309) / 309] x 100
Subtract the new number by the original number
329 - 309 = 20
20 ÷ 309 = 0.06472491909385113
0.06472491909385113 x 100 = 6.47%