| 年度 | 实际值 |
|---|---|
| 1995 | 26.8 |
| 1996 | 27.5 |
| 1997 | 47.58 |
| 1998 | 24.5 |
| 1999 | 23.5 |
| 2000 | 21.6 |
| 2001 | 23.65 |
| 2002 | 25.86 |
| 2003 | 22.95 |
| 2004 | 21.89 |
| 2005 | 22.1 |
| 2006 | 21.13 |
| 2007 | 22.38 |
| 2008 | 20.32 |
| 2009 | |
| 2010 | 19.09 |
| 2011 | 18.02 |
| 2012 | 17.32 |
| 2013 | 17.03 |
| 2014 | 16.66 |
| 2015 | 16.89 |
| 2016 | 16.69 |
| 2017 | 13.33 |
| 2018 | 12.42 |