Does anyone know the average of how much money mangakas get in Europe America and Japan?

A Mangaka doesn't get paid salary. They get paid for whatever they sold.

The average Mangaka works roughly 8-10 hours a day. Generally they have to give in 20-40 pages of manga a month so it's one compleated page every day (not including the time it takes to write the story). If the editor doesn't like it the Mangaka has to re-do it. Also the extra art like cover art or graphic books.

You don't get an hourly rate but a contract based partially on sales, the average contract is usually for a beginner 500$ per 20 pg's.

Assuming it takes 5 hours per page about 5$ per hour.

If the Managaka's just starting then they're looking at self publishing which is Doujinshi. In that case they make what they sell after paying their own printing fee.

They have to then calculate their costs; time to make the comic, materials used, paying assistances, ect. ect. ect.

In the end the profit is compleatly dependent on the Mangaka.