Rough sleeping has increased by 120% in England but has fallen in Scotland.
Such phrases describing growth rate as in the above examples are very common, but sometimes I'm confused about how to read them correctly.
My understanding is:
If our 2019 sales are up 120% (or has increased 120%) from year 2018, it means, for instance, US$ 100 million in 2018, and US$ 120 million in 2019
If our 2019 sales are up by 120% (or has increased by 120%) from year 2018, it means, for instance, US$ 100 million in 2018, and US$ 220 million in 2019
If the above understanding is correct, then how should I interpret "..... is up 20% from last year"? Is it different from "up 120% from last year"?
Or maybe those expressions include some ambiguities?