You're going to have to draw the meaning out a bit more for me, continuing with the assumption that "Americans" means the US then they score 69.8 vs a list top of 73.2. Given that the list sets out to compare the incomparable that seems pretty much equivalent. The US's worst score in its worst scoring category is "Sustainable Trade" which is driven more by their historically dominant military position than anything else and not all that relevant to their corporate governance policies.

And there are a huge number of subjective judgements about what the worth of individual categories is, especially given the political nature of quality. Picking on one of my favourites - the US scores low on "Income Inequality". Income inequality is a weird measure because we'd expect the poorest people in society to have literally nothing (because some people are beyond help). Therefore the wealthier a society is and the more income inequality I'd expect as a baseline. People get worked up about it even though in practice it is a struggle to articulate how it is even a good or bad thing.