| Value | Category | Cases | |
|---|---|---|---|
| 1993 | 1 |
0.2%
|
|
| 1994 | 1 |
0.2%
|
|
| 1995 | 3 |
0.6%
|
|
| 1996 | 9 |
1.7%
|
|
| 1997 | 505 |
97.3%
|
|
| Sysmiss | 402 |