Online job advertisements for recruiters and staffing professionals in September increased 12 percent from September 2011 to more than 14,000, according to Wanted Analytics, a firm that tracks online job ads. Compared to the same time period in 2010, ads are up 29 percent.

New York, Washington, D.C., Chicago, Los Angeles, and San Francisco had the highest volume of listings during September. The New York metro area saw the most available positions, but San Francisco experienced the greatest growth in demand over the past year at 36 percent.

Desired skill sets included applicant tracking software, full lifecycle recruiting, negotiation and social media skills. Compared to September 2011, the number of job ads seeking candidates with strong negotiation abilities is up 13 percent and ads with social media requirements are up 52 percent.