The regional distribution of included study periods
| Region | Country |
| Asia=11 | China=2; Iran=1; Japan=5; Saudi Arabia=2; Russia=1 |
| Australia and New Zealand=8 | Australia=7; New Zealand=1 |
| Europe=43 | Croatia=1; Denmark=1; Estonia=1; Finland=4; France=5; Georgia=1; Germany=1; Greece=2; Hungary=1; Ireland=1; Italy=12; Norway=4; Poland=1; Portugal=1; Scotland=1; Sweden=5; UK=1 |
| North America=7 | USA=7 |
| South America and Caribbean=8 | Argentina=1, Brazil=3, Barbados=1, Chile=1, Martinique=2 |