Artists perform during the opening show directed by German director Volker Hesse, on the opening day of the Gotthard rail tunnel, at the fairground Rynaecht at the northern portal in Erstfeld, Switzerland, Wednesday, June 1, 2016. The construction of the 57 kilometer long tunnel began in 1999, the breakthrough was in 2010. After the official opening on June 1, the commercial operation will start in December 2016. (Photo by Ruben Sprich\Pool Photo via AP Photo)

Riot police clash with protesters during a rally to demand a referendum to remove Venezuela's President Nicolas Maduro in Caracas, Venezuela, September 1, 2016. (Photo by Marco Bello/Reuters)

A worker cleans a dragon ahead of the upcoming Chinese Lunar New Year celebrations at the Boen Tek Bio temple in Tangerang, Banten province, Indonesia February 1, 2016. (Photo by Reuters/Beawiharta)

Luxury buildings are reflected in front of houses at a lake dwelling also known as or palafitte or “Palafito” in Recife, Brazil, March 1, 2016. Zika has spread most rapidly in the urban squalor of Brazil's northeastern coastal cities like Recife. (Photo by Ueslei Marcelino/Reuters)

A woman and a child make a bonfire at a makeshift camp for migrants and refugees at the Greek-Macedonian border near the village of Idomeni, Greece, April 1, 2016. (Photo by Marko Djurica/Reuters)

Ethnic Wa performer dressed as United Wa State Army (UWSA) soldiers perform a traditional dance in Mongmao, Wa territory in northeast Myanmar October 1, 2016. (Photo by Soe Zeya Tun/Reuters)

A refugee sits in front of a Greek riot police cordon during a protest at the Greek-Macedonian border, near the Greek village of Idomeni, March 1, 2016. (Photo by Alexandros Avramidis/Reuters)

Local residents fight to collect free drinking water from municipal corporation tanker on a hot summer day on the outskirts of Ahmedabad, India June 1, 2016. (Photo by Amit Dave/Reuters)