Farmer Zhang Xianping rides his pig "Big Precious" during an interview with the media, in Zhangjiakou, Hebei province, China, November 2, 2015. Zhang, a pig breeder, instead of killing it, decided to keep the two-year-old "Big Precious" as pet when its weight reached 600 kg, according to local media. (Photo by Reuters/China Daily)

A hot air balloon in tortoise shape flies in the air during the Tazaungdaing air balloon festival in Pyin Oo Lwin, Myanmar, 25 November 2015. During the festival, hot air balloons made of multicolored papers and hung with paper lanterns, fireworks and fire sticks are exploded in mid-air. (Photo by Hein Htet/EPA)

A reflection of the Alps mountain “Nordkette” is seen in the ski googles of Anders Bardal of Norway during the training round of the FIS Ski Jumping World Cup event at the 60th Four Hills ski jumping tournament at Bergisel on January 3, 2012 in Innsbruck, Austria. (Photo by Alexander Hassenstein/Bongarts/Getty Images)

Visitors view the work entitled “Golden Jubilee” by Chinese artist Xin Dongwang at the “Extension and Integration: A Circuit Exhibition In Hubei Of Study on the Modern Chinese Oil Painting” at the Hubei Museum of Art on March 8, 2009 in Wuhan of Hubei Province, China. (Photo by China Photos/Getty Images)

Brett Gardner #11of the New York Yankees dives into second base on the back end of an attempted double during the first inning in a MLB baseball game at Yankee Stadium on September 3, 2014 in the Bronx borough of New York City. Gardner was tagged out on the play. (Photo by Rich Schultz/Getty Images)

A Chimpanzee opens its Christmas presents at ZSL Whipsnade Zoo on December 17, 2013 in Bedfordshire, England. (Photo by Tony Margiocchi/Barcroft Media)

South Asian countries in terms of total contribution of travel and tourism to GDP. #6. Vietnam, Total GDP: USD 202.6 billion (2016). Contribution of Travel and Tourism to GDP: 9.1% . Here: A boat in the Thu Bon River, Hoi An, Vietnam. (Photo by Domingo Leiva/Getty Images)

Mamoni Mandal, member of the Rapid Action Force (RAF), attends a training session at a police training school in Kolkata April 15, 2007. (Photo by Parth Sanyal/Reuters)