Two-thirds of L.A.-area small business owners increased their sales last year, but only 29 percent anticipate adding staff this year, according to an annual Union Bank of California survey.

The survey of about 350 small business owners in Los Angeles County also showed that workers’ compensation insurance is the top concern for 39 percent of small business owners, followed by competition (33 percent) and the overall condition of the California economy.

Also, L.A. County small businesses fared a little better than their counterparts in the rest of the state when it came to offering health insurance: 52 percent offered coverage versus 48 percent in the rest of the state.

The cost of healthcare and other employee benefits may help explain why so few small business owners plan to hire more workers this year, despite their overall optimism about business conditions.

“The extremely tight labor market and rising wages are perhaps making small businesses rely more on technology for productivity gains,” said Keiko Matsuda, senior economist for Union Bank.