We’re heading into the open enrollment season for benefits at many companies. When it comes to employer-sponsored health insurance plans it’s a classic case of “on the one” and “on the other hand.”

On the one hand, the increase for health benefit costs in 2012 will average 5.4%. That’s the smallest increase since 1997, according to human resource consultants Mercer.

On the other hand, health benefit cost growth remains well above both the rise in consumer inflation and the growth in workers’ earnings. Look at this chart.

The survey’s preliminary results are based on responses from some 1,600 employers through September 8.