NEW YORK (AP) — Small businesses increased their hiring in May, but at a slower pace than earlier in the year, according to a private survey released Thursday.

ADP, the company that provides payroll services, reported that small businesses added 67,000 jobs during the month. ADP's numbers reflect hiring trends at the smallest of employers, those with fewer than 50 workers.

The May number followed a gain of 57,000 small business jobs during April. That's down from the average 100,000 jobs that small employers added from January through March, ADP said.

The report provided more evidence that company owners remain uncertain about the economy and that they're unwilling to make significant staff additions until they feel more confident, not only about the economy, but also about their own sales. Other reports, including the monthly small-business optimism survey by the National Federation of Independent Business, have also said owners are very cautious.

The ADP's small-business report is part of the company's broader look at hiring by businesses of all sizes. That report also shows modest hiring during May, a sign that the job market is still recovering only slowly from the recession.

The Labor Department releases its report on employment during May on Friday.