| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
3.7%
|
| 1977 | 1 |
3.7%
|
|
| 1983 | 1 |
3.7%
|
|
| 1987 | 1 |
3.7%
|
|
| 1991 | 2 |
7.4%
|
|
| 1993 | 1 |
3.7%
|
|
| 1998 | 2 |
7.4%
|
|
| 2000 | 1 |
3.7%
|
|
| 2005 | 1 |
3.7%
|
|
| 2006 | 1 |
3.7%
|
|
| 2008 | 1 |
3.7%
|
|
| 2010 | 4 |
14.8%
|
|
| 2013 | 1 |
3.7%
|
|
| 2015 | 1 |
3.7%
|
|
| 2016 | 1 |
3.7%
|
|
| 2017 | 1 |
3.7%
|
|
| 2018 | 2 |
7.4%
|
|
| 2019 | 1 |
3.7%
|
|
| 2020 | 2 |
7.4%
|
|
| 2021 | 1 |
3.7%
|
|
| Sysmiss | 130 |