| 年度 | 实际值 |
|---|---|
| 1995 | 30.7 |
| 1996 | 30.6 |
| 1997 | 27.51 |
| 1998 | 26.4 |
| 1999 | 26.8 |
| 2000 | 23.3 |
| 2001 | 23.26 |
| 2002 | 21.99 |
| 2003 | 17.45 |
| 2004 | 18.25 |
| 2005 | 17.93 |
| 2006 | 16.68 |
| 2007 | 13.6 |
| 2008 | 14.41 |
| 2009 | |
| 2010 | 12.73 |
| 2011 | 12.63 |
| 2012 | 12.3 |
| 2013 | 12.48 |
| 2014 | 11.59 |
| 2015 | 10.73 |
| 2016 | 10.53 |
| 2017 | |
| 2018 | 8.97 |