| Value | Category | Cases | |
|---|---|---|---|
| -1 | True missing | 5 |
0.1%
|
| 98 | Don't know | 17 |
0.3%
|
| 1998 | 17 |
0.3%
|
|
| 1999 | 26 |
0.5%
|
|
| 2000 | 94 |
1.7%
|
|
| 2001 | 76 |
1.4%
|
|
| 2002 | 132 |
2.4%
|
|
| 2003 | 312 |
5.7%
|
|
| 2004 | 533 |
9.7%
|
|
| 2005 | 786 |
14.3%
|
|
| 2006 | 1036 |
18.9%
|
|
| 2007 | 1021 |
18.6%
|
|
| 2008 | 849 |
15.5%
|
|
| 2009 | 476 |
8.7%
|
|
| 2010 | 88 |
1.6%
|
|
| 2011 | 12 |
0.2%
|
|
| 2012 | 1 |
0%
|