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Distribution of included studies by region
| Region | Number of studies (%) |
|---|---|
| Africa |
1 (1.0) |
| Asia |
15 (13.9) |
| Australia |
4 (3.7) |
| Europe |
33 (30.6) |
| North America |
29 (26.9) |
| South America |
7 (6.5) |
| Worldwide or multi-country |
19 (17.6) |
| Total | 108 (100.0) |
