| Value | Category | Cases | |
|---|---|---|---|
| 1980 | 6 |
0%
|
|
| 1981 | 7 |
0%
|
|
| 1982 | 31 |
0%
|
|
| 1983 | 52 |
0%
|
|
| 1984 | 86 |
0.1%
|
|
| 1985 | 151 |
0.1%
|
|
| 1986 | 222 |
0.1%
|
|
| 1987 | 311 |
0.2%
|
|
| 1988 | 474 |
0.3%
|
|
| 1989 | 621 |
0.4%
|
|
| 1990 | 953 |
0.6%
|
|
| 1991 | 1048 |
0.7%
|
|
| 1992 | 1537 |
1%
|
|
| 1993 | 1701 |
1.1%
|
|
| 1994 | 2056 |
1.3%
|
|
| 1995 | 2594 |
1.6%
|
|
| 1996 | 2791 |
1.8%
|
|
| 1997 | 3269 |
2.1%
|
|
| 1998 | 3734 |
2.4%
|
|
| 1999 | 4175 |
2.6%
|
|
| 2000 | 4659 |
3%
|
|
| 2001 | 4689 |
3%
|
|
| 2002 | 5183 |
3.3%
|
|
| 2003 | 5812 |
3.7%
|
|
| 2004 | 5924 |
3.8%
|
|
| 2005 | 6799 |
4.3%
|
|
| 2006 | 6595 |
4.2%
|
|
| 2007 | 7249 |
4.6%
|
|
| 2008 | 7595 |
4.8%
|
|
| 2009 | 8059 |
5.1%
|
|
| 2010 | 8961 |
5.7%
|
|
| 2011 | 8242 |
5.2%
|
|
| 2012 | 8836 |
5.6%
|
|
| 2013 | 8339 |
5.3%
|
|
| 2014 | 8736 |
5.5%
|
|
| 2015 | 8463 |
5.4%
|
|
| 2016 | 8333 |
5.3%
|
|
| 2017 | 8639 |
5.5%
|
|
| 2018 | 802 |
0.5%
|
|
| 9997 | Inconsistent | 62 |
0%
|
| 9999 | No response | 103 |
0.1%
|