From crime rates to life expectancy to income levels, statistics at the national level are next to useless when it comes to measuring the daily lives of ordinary people in the United States. This is because the United States — which is a huge and geographically diverse country — is simply too large to be summed up in a single number. This sort of generalizing is inappropriate for pretty much any place that's larger than a single metro area, but it's especially bad when applied to a place like the United States. Even the larger European countries are much...