Story highlights Crime rates have been declining for years

Most crimes are committed by people known to the victims

But perception of crime doesn't always match statistics

Many U.S. residents believe crime is getting worse

You can't escape the headlines. An Australian going to college in the United States is gunned down by teens who police say killed him out of boredom. A few days later, a World War II veteran is beaten to death for reasons still unknown.

The death of Australian Christopher Lane in Duncan, Oklahoma, even sparked calls for Aussies to boycott travel to the United States because of all the violence.

Two shocking, high-profile crimes, one question: "What the hell is going on!?" Facebook user Stacey James Gordon wrote on CNN's Facebook page.

"This country better wake up ...our youth have serious issues," Heather Chesser wrote.

Although the cases have struck a nerve with their disturbing randomness and apparent cruelty, the reality is that living in the United States may never have been safer, and you're much more likely to be the victim of a crime committed by someone you know than you are to be assaulted by a stranger.

Nearly eight of every 10 murders in the United States between 1993 and 2008 were committed by someone the victim knew, according a 2010 report by the federal Bureau of Justice Statistics. The report didn't include figures for 2011 or 2012.

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Similarly, nearly two out of every three nonviolent crimes were committed by someone the victim knew.

Pair that with figures on overall crime: According to the FBI, the violent crime rate in the United States is about half what it was in 1992.

And between 1992 and 2011, the annual number of murders in the United States fell from 23,760 to 14,612 despite a growing population.

Rape, robbery, assault, even property crimes also fell in a well-documented decline that has gone on for years, albeit with a small upturn in 2012.

Criminologists have cited shifts in the crack cocaine market, which drove many 1990s-era murders; an increase in the number of offenders behind bars; the country's aging population; and more sophisticated policing for the declines.

But perceptions of crime haven't always followed the reality.

In May, a Pew Research Center study found that 56% of Americans believe that gun violence is higher than it was 20 year ago, even though it has fallen precipitously since the 1990s.

And in 2011, Gallup found that 68% of Americans believed crime was getting worse, despite the reality of declining crime rates nationwide.