-3.5% is the change from 343 to 331
Calculation steps:
[( 331 - 343 ) ÷ 343] x 100 = -3.5%
Formula
Percentage change = [(331 - 343) / 343] x 100
Subtract the new number by the original number
331 - 343 = -12
-12 ÷ 343 = -0.03498542274052478
-0.03498542274052478 x 100 = -3.5%