How much do song writers get paid?

The song writer may be paid by the following:

• The type of person he had given the song. If it's a big star then surely he/she would get a great salary
• Depending on his career if he's popular to that line then surely when someone ask him to write a song or he writes a song for the star then he/she would get much money.
• How much is the sale of the song to the people