A man rides a horse at a playground on a hill in Kabul April 19, 2015. (Photo by Mohammad Ismail/Reuters)

A boy dressed as the Star Wars character Darth Vader attends a Star Wars themed church service, at the Zion Church in Berlin, Sunday, December 20, 2015. About 500 people, some carrying light saber props or wearing Darth Vader masks, attended the service, more than twice as many as usual on a Sunday. (Photo by Markus Schreiber/AP Photo)

Participants prepare backstage during Belarus bodybuilding and fitness championship in Minsk April 25, 2015. (Photo by Vasily Fedosenko/Reuters)

A six-year-old acrobat performs on the opening of a tourist festival in Bozhou, Anhui province, China May 3, 2015. (Photo by Reuters/China Daily)

A mahout splashes water on his elephant in the river Sabarmati on a hot summer day in Ahmedabad, India, May 20, 2015. (Photo by Amit Dave/Reuters)

A Dandy Dinnmont Terrier is displayed at the World Dog Show in Rho, near Milan, Italy, Saturday, June 13, 2015. (AP Photo/Luca Bruno)

A gibbon drinks from a soft drink bottle, given by a tourist, at a zoo in Kunming, Yunnan province, June 18, 2015. (Photo by Wong Campion/Reuters)

A reveller smiles as she walks in the rain at Worthy Farm in Somerset during the Glastonbury Festival in Britain, June 28, 2015. (Photo by Dylan Martinez/Reuters)