Based on BLS data…
http://www.bls.gov/ooh/education-training-and-library/high-school-teachers.htm#tab-5
For comparison, the median annual wage in Chicago is $71,000+ a year.
I don’t think the issue is attrition (that 13% number is junk), but recruiting and developing good teachers. While additional funding could help, it’s an issue that has to be attacked from several angles. One, not often discussion item, would be better administrative management. Who your boss is matters, especially for job satisfaction. Improving job satisfaction would help with retaining and developing good teachers.