Think what that means in absolute numbers - US has a population of around 350 million? I think. 15% is equivalent to around 45 million people.
I have traveled extensively to the US over the years on business, and, given the wealth of the country I have been shocked to see.
I have seen 100s if not thousands of people queueing up overnight in the hope of getting a free basic health check from a charity - some have traveled 100s of miles in order to attend. This, in the richest country in the world.
Its a salutary reminder of how lucky people are in the UK having the NHS.