No way to compare them. People would be absolutely shell shocked to see what their insurance actually costs compared to the percentage they pay through their employer.
There is no way for a private individual to negotiate rates based on diversified risk. When your employer negotiates with an insurer, they can get a lower overall rate because individual risk is spread over a large pool of participants.
Of course it COULD be, and in all honesty, it should be. The issue is that in real life it wont be. Our govt has proven that it can do absolutely nothing in a smart or efficient way. Under govt control, health care will go from 17% of GDP to 25% in 5 years and top 30% in 10 years. You can bank on that.