| Value | Category | Cases | |
|---|---|---|---|
| 2015 | 20 |
0.6%
|
|
| 2016 | 258 |
7.2%
|
|
| 2017 | 233 |
6.5%
|
|
| 2018 | 78 |
2.2%
|
|
| 9997 | 7 |
0.2%
|
|
| 9999 | NO RESPONSE | 18 |
0.5%
|
| Sysmiss | 2946 |
82.8%
|