-0.64% is the change from 311 to 309
Calculation steps:
[( 309 - 311 ) ÷ 311] x 100 = -0.64%
Formula
Percentage change = [(309 - 311) / 311] x 100
Subtract the new number by the original number
309 - 311 = -2
-2 ÷ 311 = -0.006430868167202572
-0.006430868167202572 x 100 = -0.64%