| Year | Number of sites | Area (square km) | Area (ha) |
|---|---|---|---|
| 1971 | 1 | 51.77 | 5177 |
| 1991 | 2 | 68.68 | 6868 |
| 1992 | 3 | 125.1 | 12510 |
| 1993 | 4 | 185.42 | 18542 |
| 1998 | 306 | 664.67 | 66467 |
| 2000 | 307 | 839.23 | 83923 |
| 2003 | 308 | 1431.5 | 143150 |
| 2005 | 309 | 1567.76 | 156776 |
| 2013 | 310 | 1893.86 | 189386 |
| 2018 | 311 | 2106.96 | 210696 |