| 年度 | 实际值 |
|---|---|
| 1992 | 18.2 |
| 1993 | |
| 1994 | |
| 1995 | 18.5 |
| 1996 | |
| 1997 | |
| 1998 | |
| 1999 | 18.28 |
| 2000 | 182039 |
| 2001 | 182038 |
| 2002 | 14.6888 |
| 2003 | 14.6985 |
| 2004 | 14.7797 |
| 2005 | 14.7712 |
| 2006 | 14.91 |
| 2007 | 15.04 |
| 2008 | 15.14 |
| 2009 | 15.3144 |
| 2010 | 15.6163 |
| 2011 | 15.766 |
| 2012 | 15.89 |
| 2013 | 15.83 |
| 2014 | 16.1 |
| 2015 | 14.37 |
| 2016 | 14.83 |