Two words describe how American public middle school teachers compare to other wealthy countries: Overworked and underpaid.

American teachers in such schools spend more time teaching than peers in other member countries of the Organisation for Economic Co-operation and Development (OECD), a economic research group that focuses on the world’s more affluent countries.

However, they earn only 70 percent of what workers with similar levels of education make. On average, teachers in public middle schools in OECD countries earn roughly 85 percent of what similarly educated workers bring home.

OECD’s annual report on education, released in September, indicates that teachers’ salaries play a major role in the attractiveness of the teaching job. Salaries have a direct impact on coaxing new graduates to pursue a teaching career and keeping them in the profession.

The relatively high workload and low pay could help explain the 14 percent annual teacher turnover rate in all schools in the U.S. In comparison, schools in the world’s top performing school systems: South Korea, Finland and Singapore, see a very low turnover rate — 1 percent, 2 percent and 3 percent respectively.

“Roughly half a million U.S. teachers either move or leave the profession each year — attrition that costs the United States up to $2.2 billion annually,” said a 2014 report from the Alliance for Excellent Education.

In particular, teacher attrition has a severe impact on those hard-to-staff schools with disproportionately serve low-income students and students of color.