WASHINGTON (AP) — The government says it recovered almost $8 for each dollar it spent investigating health care fraud over the past three years, including a record $4.2 billion last year.

The $7.90 average return on investment is the highest in the 16-year history of the Health Care Fraud and Abuse Program. Since 1997, the program — a joint effort of the departments of Justice and Health and Human Services — has returned more than $23 billion to the Medicare trust funds.

Overall, the Justice Department opened more than 1,100 criminal health care fraud investigations last year involving 2,148 potential defendants. More than 800 defendants were convicted of health care fraud-related crimes during the year and the department opened nearly 900 new civil investigations.