The rate at which Americans commit suicide with guns has been increasing for several years, even as the rate of gun homicides has declined. Research shows that the increase is correlated with higher gun ownership. Public health experts say ready access to firearms makes it easier for people to act on suicidal thoughts. And about 85 percent of suicide attempts that involve guns are successful, compared with less than 3 percent of those involving drug overdoses. Over all, guns were used in about half of the 41,000 suicides in 2013, the latest year for which there is data from the Centers for Disease Control and Prevention.