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Distribution of the Observational Studies by Country
| Country | No. of Studies |
|---|---|
| United States | 55 |
| Japan | 10 |
| United Kingdom | 10 |
| Australia | 7 |
| France | 7 |
| Finland | 5 |
| Italy | 5 |
| Switzerland | 4 |
| India | 3 |
| Netherlands | 3 |
| Turkey | 3 |
| Brazil | 1 |
| Canada | 1 |
| Croatia | 1 |
| Denmark | 1 |
| Serbia | 1 |
| Taiwan | 1 |
