# Country Value in 2012 Value in 2016 Value in 2018 1 Switzerland 52,519 67,367 63,781 2 United Kingdom 3,326 14,920 25,772 3 United States 27,154 19,749 18,138 4 South Africa 20,436 20,670 17,882 5 Australia 13,530 20,498 16,091 6 United Arab Emirates 14,745 26,979 15,369 7 Canada 3,730 6,415 12,921 8 Hong Kong 48,312 29,334 12,076 9 Singapore 4,640 5,537 10,128 10 Ghana 7,203 9,411 10,030 11 Japan 6,122 8,599 7,293 12 Peru 9,686 6,251 7,076 13 Mexico 8,379 5,388 4,824 14 Germany 11,037 5,017 4,665 15 Thailand 6,451 6,942 4,414 16 Burkina Faso 274 3,019 4,281 17 Turkey 13,152 12,011 3,209 18 Brazil 3,080 3,346 2,973 19 Guinea 354 1,541 2,789 20 Venezuela 285 2,922 2,710