-2.01% is the change from 399 to 391
Calculation steps:
[( 391 - 399 ) ÷ 399] x 100 = -2.01%
Formula
Percentage change = [(391 - 399) / 399] x 100
Subtract the new number by the original number
391 - 399 = -8
-8 ÷ 399 = -0.020050125313283207
-0.020050125313283207 x 100 = -2.01%