99.4% is the change from 497 to 991
Calculation steps:
[( 991 - 497 ) ÷ 497] x 100 = 99.4%
Formula
Percentage change = [(991 - 497) / 497] x 100
Subtract the new number by the original number
991 - 497 = 494
494 ÷ 497 = 0.993963782696177
0.993963782696177 x 100 = 99.4%