Ingots of 99.99 percent pure silver are cast at the Krastsvetmet Krasnoyarsk non-ferrous metals plant in the Siberian city of Krasnoyarsk, Russia, June 5, 2015. Krastsvetmet is one of the world's largest players in the precious metals industry. REUTERS/Ilya Naymushin

A partially burned American flag lies on the street near the spot where Michael Brown was killed before an event to mark the one year anniversary of his killing in Ferguson, Missouri August 9, 2015. (Photo by Rick Wilking/Reuters)

A working team appointed by the Archaeological Superintendence of Pompeii performs a Cat scan (Computerized axial tomography) one out of thirty casts of victims of the eruption of Vesuvius in 79 AD in Pompeii, in Napoli, Italy, 29 September 2015. The project which aims to trace the habits of life, employment and social class of the victims, involves a working team of archeologists, anthropologists, radiologists, dentists and engineers to obtain results from the scan. (Photo by Cesare Abbate/EPA)

Participants wearing historical attire compete on historical high wheel Penny Farthing bicycles in the traditional 'One Mile Race' at Letna Park in Prague, Czech Republic, November 7, 2015. The meeting of Penny Farthing bicycles is taking place for the 22th time. (Photo by Filip Singer/EPA)

Prince Charles, Prince of Wales (R) and Camilla, Duchess of Cornwall (L) visit Seppeltsfield Winery in Barossa Valley, Australia, 10 November 2015. The royal couple are on a 12-day tour visiting seven regions in New Zealand and three states and one territory in Australia. (Photo by Daniel Kalisz/EPA)

Ramela Meseljevic, a 7 year-old girl born without both of her hands and one of her legs shorter than the other, writes during classes in the her school in Begov Han, Bosnia and Herzegovina December 2, 2015. International Day of Disabled Persons is observed on December 3 with the theme "Inclusion matters: access and empowerment of people of all abilities". (Photo by Dado Ruvic/Reuters)

A contestant lies in a chili covered pool eating Chillies during a chili eating contest on July 8, 2018 in Ningxiang, Hunan Province of China. Citizen Tang Shuaihui ate 50 Chillies in one minute winning the contest. (Photo by VCG/Getty Images)

A person rides on a zip-line descending from the second floor of the Eiffel Tower on May 28, 2019 in Paris. The 800 meter crossing takes one minute at a speed of 90km/h. The zip-line will be opened from May 29 to June 2, 2019. (Photo by Francois Guillot/AFP Photo)