| Value | Category | Cases | |
|---|---|---|---|
| 1 | Only when assignements are given | 19 |
8.8%
|
| 2 | On request | 10 |
4.6%
|
| 3 | Assigned the book without restrictions | 16 |
7.4%
|
| 5 | Missing | 1 |
0.5%
|
| 6 | Other | 4 |
1.9%
|
| 9 | Not applicable | 166 |
76.9%
|