The percentage of Massachusetts employers offering health insurance coverage is holding steady and is substantially higher than before the passage of the state's pioneering health care reform legislation, according to a survey.

Last year, 77% of Massachusetts employers offered coverage to employees, virtually unchanged from 76% in 2009 but up from 70% in 2005, the year before the passage of the state's health care reform legislation, according to the survey by the Massachusetts Division of Health Care Finance and Policy.

Under the 2006 law, employers with at least 11 employees are assessed an annual fine of $295 for each full-time employee that is not offered qualified coverage.

Virtually all employers with more than 50 employees offer coverage. Last year, 97% of employers with at least 51 employees provided coverage, compared with 98% in 2009. Coverage in 2010 dipped to 89%—down from 92% in 2009—among employers with between 11 and 50 employees, but edged up to 69% from 67% in 2009 among employers with between three and 10 employees.

Contrasting surveys

The maintenance of employer coverage in Massachusetts, whose law in certain ways was a model for last year’s federal health care reform law, contrasts with some other surveys that found that a significant percentage of employers would drop coverage after key portions of the Patient Protection and Affordable Care Act go in effect in 2014.

For example, a McKinsey & Co. survey of more than 1,300 employers of varying sizes found that more than 30% of respondents “definitely” or “probably” would drop coverage after 2014. On the other hand, only 6% of employers with at least 500 employees and 20% of employers with 10 to 499 employees responding to a Mercer L.L.C. survey said it was likely they would drop coverage in 2014.

The Massachusetts survey also found that group health insurance premiums continued to rise. In 2010, the median monthly premium for individual coverage rose to $479, an 8.4% increase; the median monthly premium for family coverage climbed to $1,262, an increase of about 6.1%.

The survey is based on the responses of 774 employers.