Who has the worst health system? Answer: US by any measure.

So if we plot the total health spending (public + private) per capita against the average life expectancy we get a crude measure of the effectiveness of the health system. As can be seen the US spends far more than any country with no actual improvement in life expectancy. You are just as likely to die as someone in Chile.

Specifically about efficiency US is by far the least efficient health system wasting huge amounts of money with no improvements in life expectancy.

Now both graphs are skewed. Japan and UK both achieve the same life expectancy per $ spent on health care so their systems are comparable. This is clear in the second graph, not in the first. But a country that spends nothing on healthcare gets an infinite efficiency so the second graph becomes less meaningful as spending reduces.