-3.01% is the change from 399 to 387
Calculation steps:
[( 387 - 399 ) ÷ 399] x 100 = -3.01%
Formula
Percentage change = [(387 - 399) / 399] x 100
Subtract the new number by the original number
387 - 399 = -12
-12 ÷ 399 = -0.03007518796992481
-0.03007518796992481 x 100 = -3.01%