Forex How many traders around the world?

Hello, i'm looking for an information.

The question is:

How many traders/investors, (both retails and institutionals) that trade any kind of markets, forex, stocks, futures, equities, commodities, various derivatives (there are tons of weird instruments that most of us fx retails have never heard of), in any country, in the whole world, do actually exist?

Is there a way (a source of information) to find out approximately such number?

Source.