Appendix 1.
Level I studies broken down by country and year.
| Year | Total | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| 1980 | 1985 | 1990 | 1995 | 2000 | 2005 | 2010 | |||
| Country | Australia | 0 | 0 | 0 | 0 | 0 | 1 | 1 | 2 |
| Canada | 0 | 0 | 0 | 0 | 0 | 2 | 3 | 5 | |
| China | 0 | 0 | 0 | 0 | 0 | 1 | 1 | 2 | |
| Collaborative | 0 | 0 | 0 | 0 | 1 | 2 | 2 | 5 | |
| Denmark | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 1 | |
| Finland | 0 | 0 | 0 | 0 | 0 | 0 | 2 | 2 | |
| France | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | |
| Germany | 0 | 0 | 0 | 0 | 0 | 0 | 2 | 2 | |
| Greece | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | |
| Italy | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | |
| Netherlands | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 2 | |
| Norway | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | |
| South Korea | 0 | 0 | 0 | 0 | 0 | 2 | 1 | 3 | |
| Sweden | 0 | 0 | 0 | 2 | 0 | 1 | 0 | 3 | |
| Switzerland | 0 | 0 | 0 | 1 | 0 | 0 | 1 | 2 | |
| Taiwan | 0 | 0 | 0 | 0 | 0 | 2 | 0 | 2 | |
| UK | 0 | 0 | 1 | 0 | 0 | 2 | 3 | 6 | |
| USA | 3 | 9 | 12 | 11 | 5 | 20 | 8 | 68 | |
| Total | 3 | 10 | 13 | 14 | 7 | 35 | 27 | 109 |