| DVI | 2001 | 2007 | ||||||
| Category | Values | Area (km2) | % | Values | Area (km2) | % | ||
| I | 114 | 142 | 4.13 | 4.79 | 97 | 142 | 13.56 | 15.72 |
| II | 142 | 155 | 9.39 | 10.88 | 142 | 155 | 10.03 | 11.62 |
| III | 155 | 170 | 8.76 | 10.16 | 155 | 170 | 27.43 | 31.79 |
| IV | 170 | 182 | 41.70 | 48.32 | 170 | 182 | 29.31 | 33.97 |
| V | 182 | 198 | 22.32 | 25.86 | 182 | 193 | 5.96 | 6.90 |
| 86.29 | 100.00% | 86.29 | 100.00% | |||||