http://crimeresearch.org/2014/03/comparing-murder-rates-across-countries/I like this article.
It has the information we are discussing in chart form.
Plus a long discussion of how this information is gathered! This is where the real dirt is.
I learn from this that the reports of murder are generally reliable in the US , so though it is not easy, it is possible to compile meaningful stats.
In most countries the standard is different , generally lower.
In particular the way that England reports homicide . A homicide is only reported as such if there is a conviction for homicide associated with it.
This is not really cheating, they have always had different rules, the problem is that these different standards make a useful comparison difficult , or impossible.
If all murders were counted the same way, then the ranking of the US would improve significantly.
And as it is the US is better than the world average.