Gun enthusiasts look over Smith & Wesson pistols at the NRA Annual Meetings & Exhibits on May 21, 2016 in Louisville, Kentucky. About 80,000 visitors are expected to attend the three-day event. (Photo by Scott Olson/Getty Images)

Two race pigs jump over an obstacle during a rural festivity in reference to Maria Ascension in San Bernardino, Switzerland on Monday, August 15 2016. (Photo by Samuel Golay/Keystone/TI-Press via AP Photo)

A police officer lies on the street after being run over by a bus during a protest against the increase in the price of public transport in San Cristobal, Venezuela March 29, 2016. (Photo by Carlos Eduardo Ramirez/Reuters)

An Afghan National Army (ANA) helicopter flies over a soldier during a training exercise at the Kabul Military Training Centre in Afghanistan October 7, 2015. (Photo by Ahmad Masood/Reuters)

A rabbit jumps over a hurdle at an obstacle course during the first European rabbit hopping championships, which Lada Sipova-Krecova of Czech Republic won, on October 30, 2011 in Wollerau, Switzerland. Rabbit hopping is a growing trend among rabbit owners in Central Europe. (Photo by Harold Cunningham/Getty Images)

Planes for Team Oracle perform over downtown San Francisco during a practice session for San Francisco Fleet Week October 5, 2007 in San Francisco, California. (Photo by Jed Jacobsohn/Getty Images)

Fireworks explode over the Quadriga statue atop the Brandenburg Gate on New Year's Eve on January 1, 2012 in Berlin, Germany. According to the media, up to one million people celebrate the country's biggest New Year's Eve Party. (Photo by Andreas Rentz/Getty Images)

The Empire State Building towers over the Manhattan skyline as tourists gather on the observation deck of Rockefeller Center on February 13, 2012 in New York City. The owner of the Empire State Building, Malkin Holdings, plans to raise up to $1 billion in an initial public offering on the 102 story Manhattan landmark. (Photo by John Moore/Getty Images)