| 年度 | 实际值 |
|---|---|
| 1995 | 22.4 |
| 1996 | 24.5 |
| 1997 | 20.88 |
| 1998 | 23.6 |
| 1999 | 25.4 |
| 2000 | 43.6 |
| 2001 | 22.26 |
| 2002 | 21.97 |
| 2003 | 20.8 |
| 2004 | 19.76 |
| 2005 | 18.28 |
| 2006 | 18.77 |
| 2007 | 17.03 |
| 2008 | 17.55 |
| 2009 | |
| 2010 | 18.1 |
| 2011 | 16.21 |
| 2012 | 13.73 |
| 2013 | 12.75 |
| 2014 | 11.55 |
| 2015 | 11.84 |
| 2016 | 11.44 |
| 2017 | 10.08 |
| 2018 | 11.11 |