| Value | Category | Cases | |
|---|---|---|---|
| 1 | Land frontier exhausted, fields are permanently cultivated | 48 |
49.5%
|
| 2 | Land frontier still open, but can be foreseen to close withi | 19 |
19.6%
|
| 3 | Land frontier open, no acute pressure on land | 30 |
30.9%
|
| -9 | 5 | ||
| -8 | 1 | ||
| -7 | 30 |