Table 2. Research location of included studies in order of quantity.
Multiple papers from the same study counted as having a single location unless reporting results from different locations.
| Continent | Quantity | Country | Quantity | Study ID(s) |
|---|---|---|---|---|
| Europe | 23 | UK | 4 | 30, 41, 44, 59 |
| Germany | 3 | 30, 37, 68 | ||
| Italy | 3 | 19, 20, 26 | ||
| Spain | 3 | 6, 22, 51 | ||
| Finland | 2 | 54, 55 | ||
| Norway | 2 | 10, 16 | ||
| Sweden | 2 | 28, 61 | ||
| Belgium | 1 | 60 | ||
| Estonia | 1 | 30 | ||
| Netherlands | 1 | 30 | ||
| Romania | 1 | 17 | ||
| North America | 16 | USA | 11 | 9, 15, 38, 40, 42, 43, 47, 50, 62, 65, 66 |
| Canada | 5 | 8, 14, 33, 58, 64 | ||
| Africa | 12 | South Africa | 4 | 1, 2, 21, 52 |
| Nigeria | 2 | 11, 39 | ||
| Burkina Faso | 1 | 46 | ||
| Ethiopia | 1 | 23 | ||
| Ghana | 1 | 46 | ||
| Tanzania | 1 | 46 | ||
| Uganda | 1 | 5 | ||
| Zambia | 1 | 67 | ||
| Asia | 9 | Indonesia | 2 | 32, 34 |
| Armenia | 1 | 27 | ||
| Bangladesh | 1 | 4 | ||
| China | 1 | 57 | ||
| Israel | 1 | 49 | ||
| Japan | 1 | 53 | ||
| Pakistan | 1 | 31 | ||
| Singapore | 1 | 57 | ||
| Australasia | 7 | Australia | 7 | 7, 18, 25, 29, 36, 56, 63 |
| South America | 3 | Brazil | 2 | 24, 48 |
| Puerto Rico | 1 | 35 |