U.S. staffing companies employed an average of 3.15 million temporary and contract workers per week in the second quarter of 2014, up 5.6 percent from the second quarter of 2013, according to data released by the American Staffing Association.

Average weekly employment in the second quarter was higher than in any second quarter since 2006, when it was 3.18 million, according to the ASA.

Staffing firm employment rose 6.2 percent from first quarter to second quarter of this year, adding more than 182,600 workers.

The ASA staffing employment and sales survey is conducted on a quarterly basis, covering approximately 10,000 establishments.