Total number of murders is meaningless. The population of a tiny country like Liechtenstein, for example, can't even begin to match the number of nutcases the United States has. It is better to compare it as a percent of the country's population.
List of countries by homicide rate - Wikipedia, the free encyclopedia
According to Wikipedia, in the latest data available, the United States isn't really that high - 5.9 murders per 100,000 inhabitants (2005), compared with El Salvador's 55.3 (2006).
I also postulate that the United States is more transparent than most other countries concerning murder rates. Look at the countries at the low end - it's not strictly comparable because of time lag. Consider as well the political ramnifications of admitting your country has a murder problem.
Thus, after doing two minutes of research, I don't believe the murder rate in the United States is that much of a cause for concern.
How ya doing, buddy?