Edit: To compare further: By median PPP-adjusted income, the US is #2, at $46k, while the Czech Republic is #26, at $21k: https://en.wikipedia.org/wiki/Median_income
By homicide rate, the US is #53, at 6.8, while the Czech Republic is #184, at 0.4: https://en.wikipedia.org/wiki/List_of_countries_by_intention...
Let this be a lesson on the importance of economy for a people's well-being.
By democracy index in 2022, CZ is 25th place, US is 30th.
It's by some margin, the richest of the "regular" rich countries.
Anyway, I've done a deep dive into the numbers. Murder rate data from the FBI has a large "unknown" category, so I'll handle that in a few ways for simplicity. Focusing on murders rather than other violent crime is the best thing to do because, while there may be a lot of ambiguity about what constitutes "assault", how often it's reported, etc., there really isn't much ambiguity about murder. We don't lose track of bodies very often. Here's the murder rate in the U.S. broken down by race. All numbers are murderers (offenders) per 100,000 people:
White (simple, ignoring "Unknown"): 1.8 Black (simple, ignoring "Unknown"): 13.3
White (assuming all "Unknown" are White): 3.7 Black (assuming all "Unknown" are Black): 23.2
White (splitting up "Unknown" by existing proportion of total): 2.6 Black (splitting up "Unknown" by existing proportion of total): 18.8
The difference is stark. Using the 2.6 vs. 18.8 raw numbers, probably closest to the truth, Black people in the U.S. are about seven times more likely to murder in a given year than are white people on average. The number becomes even more stark if you compare Black to non-Black (because Asians are less likely to murder than Whites), and yet more stark if you just look at men (women murder at something like 1/8 the rate of men, so having them in the system dilutes all differences). Hispanics are also included in "White" by the U.S. census (and they murder at higher rates than non-Hispanic Whites). Insofar as cities don't report to the UCR (like New York), if they were to report it would make the Black murder rate go up. Murder clearance ("solved") rates are abysmal in the U.S., 60-something percent on average, but are low where young black men do a lot of killing and higher elsewhere; Black Americans are more likely to get away with murder than non-Black Americans, so adjusting for that drives the Black murder rate still higher. It depends on your assumptions, but Black American men 15-35 murder at something like 50x the rate of the rest of the population.
FBI UCR murder offender data: https://ucr.fbi.gov/crime-in-the-u.s/2019/crime-in-the-u.s.-... Census data: https://www.census.gov/newsroom/press-kits/2020/population-e...