First: work out the difference (increase) between the two numbers you are comparing.
Increase = New Number – Original Number
Then: divide the increase by the original number and multiply the answer by 100.
% increase = Increase ÷ Original Number × 100.
If your answer is a negative number, then this is a percentage decrease.
Read more at: https://www.skillsyouneed.com/num/percent-change.html