Table 2 Summary of survey results by three time periods
| Â | Mf | ICT | Og4C3 | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Â | No sites | No persons | % pos | No sites | No persons | % pos | No sites | No persons | % pos |
1983–1992 | 50 | 6539 | 30.4 | 0 | 0 |  | 2 | 976 | 64.7 |
1993–2002 | 76 | 19540 | 30.1 | 35 | 8502 | 13.4 | 47 | 9755 | 56.9 |
2003–2011 | 29 | 6608 | 7.8 | 115 | 34762 | 12.8 | 27 | 5169 | 28.9 |