| 年度 | 实际值 |
|---|---|
| 1992 | 20.8 |
| 1993 | |
| 1994 | |
| 1995 | 25.2 |
| 1996 | |
| 1997 | |
| 1998 | |
| 1999 | 20.33 |
| 2000 | 202842 |
| 2001 | 202970 |
| 2002 | 12.2035 |
| 2003 | 20.2186 |
| 2004 | 20.3381 |
| 2005 | 19.6887 |
| 2006 | 21.06 |
| 2007 | 21.13 |
| 2008 | 21.65 |
| 2009 | 21.7511 |
| 2010 | 21.9123 |
| 2011 | 22.0135 |
| 2012 | 22.13 |
| 2013 | 22.43 |
| 2014 | 22.74 |
| 2015 | 7.65 |
| 2016 | 8.78 |