| Value | Category | Cases | |
|---|---|---|---|
| 1973 | 1 |
0.2%
|
|
| 1980 | 1 |
0.2%
|
|
| 1993 | 2 |
0.4%
|
|
| 1998 | 1 |
0.2%
|
|
| 2004 | 1 |
0.2%
|
|
| 2015 | 16 |
2.9%
|
|
| 2016 | 181 |
32.4%
|
|
| 2017 | 251 |
44.9%
|
|
| 2018 | 50 |
8.9%
|
|
| Missing value | 55 |
9.8%
|