How Much Does a SF/F Writer Make?

Off Tobias Buckell’s site, survey results from 74 writers: How Much Does a Science Fiction or Fantasy Writer Make?.

Summary: The typical advance for a first novel is $5000. The typical advance for later novels, after a typical number of 5-7 years and 5-7 books is $12,500. Having an agent at any point increases your advance. There is some slight correlation between number of books and number of years spent writing as represented in the 5-12.5 thousand dollar advance shift of an average of 5-7 years. Charting individual author's progressions, which I will not release to keep anonymity, reveals a large number of upward lines at varying degrees of steepness for advances, some downward slides.

Some authors noted that they'd gotten large advances in the 90s but were being paid less now.