There are 270 million guns in the United States (or about 89 for every 100 citizens). In 2011, there were 8,583 firearms homicides, down from 11,078 in 2010 (a decrease of 22.6%).
Thus, of the population of 270 million firearms, only about .003 percent are used for homicides (not accounting for the chance that multiple guns are used in some homicides). Let’s say for the sake of argument an average of 1.6 guns are used for each homicide, a not unrealistic estimate. In that case, we will push the stat up to about .005 percent.
That means around 99.995% of guns are not used for homicides each year in the United States. If guns actually caused murders, nearly 90% of the U.S. population would have been killed last year. Instead, only 0.0027 percent of the population were killed by people with firearms.