A girl presents the new Oktoberfest beer festival mug in a Oktoberfest tent in Munich, southern Germany, on August 21, 2014. The world famous beer festival Oktoberfest will takes place from September 20 to October 5, 2014. (Photo by Christof Stache/AFP Photo)

Dhruva Aliman does a back somersault as he dismounts from a slackline on the beach at Santa Monica, California on October 19, 2014. Slackline is a balance sport where a line of webbing is adjusted at different levels of tension between two anchor points and participants (called slackers) perform tricks and stunts including somersaults. (Photo by Mark Ralston/AFP Photo)

A woman offers prayers by a road as a rickshaw puller transports passengers in Kolkata October 28, 2014. (Photo by Rupak De Chowdhuri/Reuters)

A P-51 Mustang named “Charlotte's Chariot” from the Southern Heritage Air Foundation flies past a cloud of smoke and fire from a nearby battle reenactment during the Wings Over Houston Airshow in Houston, on Saturday, November 1, 2014. Battle reenactments are part of the yearly show held at Ellington Airport. (Photo by Kar Hlava/AP Photo/Bay Area Citizen)

A monkey is led by its trainer Qi Defang during training for a circus in Suzhou, Anhui province, November 29, 2014. Suzhou is known as the hometown of circus troupes in China and has more than 300 circus troupes. (Photo by William Hong/Reuters)

Horse riders perform with guns during the El-Jadida International Horse Show in El-Jadida, south of Casablanca, Morocco, October 15, 2016. (Photo by Youssef Boudlal/Reuters)

A Palestinian female masked militant from the Al-Quds Brigades, the military wing of the Islamic Jihad, takes part in an Islamic Jihad rally in Rafah, southern Gaza Strip, 29 July 2016. (Photo by Mohammed Saber/EPA)

This undated photo provided by the U.S. Fish and Wildlife Service shows two island foxes in Channel Islands National Park, Calif. Three fox subspecies native to California's Channel Islands were removed from the list of endangered species Thursday, August 11, 2016, in what federal officials have called the fastest recovery of any mammal listed under the Endangered Species Act. (Photo by Chuck Graham/U.S. Fish and Wildlife Service via AP Photo)