One question that comes up all the time in our work is what is the difference between a percentage change and a rate of increase? Answer: They are the same idea, just expressed differently. For instance, if you say the price of oil increased by 100% that is the same as saying that the price of oil doubled.
So mathematically, the 100% increase is equal to a 2.0 times increase. So generally, you can subtract one from a change factor (i.e. 2.0 times higher) to get the percentage increase.