| 年度 | 实际值 |
|---|---|
| 1993 | 25000 |
| 1994 | 23900 |
| 1995 | 23300 |
| 1996 | 20000 |
| 1997 | 22500 |
| 1998 | 21500 |
| 1999 | |
| 2000 | 20156 |
| 2001 | 20568 |
| 2002 | 22471 |
| 2003 | 21530 |
| 2004 | 20706 |
| 2005 | 19815 |
| 2006 | 19341 |
| 2007 | 19445 |
| 2008 | 21079 |
| 2009 | 19670 |
| 2010 | 18805 |
| 2011 | 19111 |
| 2012 | 19562 |
| 2013 | 19206 |
| 2014 | 19212 |
| 2015 | 19773 |
| 2016 | 19805 |
| 2017 | 19625 |