Continent | Number of included studies | Country with most included studies (and number of included studies) |
Europe | 93 | UK41 |
Australasia | 31 | Australia19 |
North America | 29 | USA18 |
Africa | 21 | South Africa21 |
Asia | 14 | Japan6 |
South America | 9 | Brazil5 |
Not specified | 1 | Not specified |