Strained by rising health care costs and the sour economy, U.S. employers are pressing workers to shoulder the added burden alone as employees pay higher insurance premiums and more out-of-pocket expenses for their medical care.

The average employer-provided family health plan now costs workers nearly $4,000 a year, up 14 percent from last year, according to a survey by the nonprofit Kaiser Family Foundation and the Health Research and Educational Trust.

That is the largest annual increase since the survey began in 1999 and a marked change from previous years when employers generally split the cost of rising premiums with their employees.