| 年度 | 实际值 |
|---|---|
| 1995 | 43.8 |
| 1996 | 41.7 |
| 1997 | 40.99 |
| 1998 | 39.5 |
| 1999 | 35.9 |
| 2000 | 34.4 |
| 2001 | 33.08 |
| 2002 | 31.64 |
| 2003 | 30.42 |
| 2004 | 31.05 |
| 2005 | 31.91 |
| 2006 | 29.43 |
| 2007 | 29.47 |
| 2008 | 27.57 |
| 2009 | |
| 2010 | 22.09 |
| 2011 | 23.36 |
| 2012 | 22.04 |
| 2013 | 17.99 |
| 2014 | 17.2 |
| 2015 | 15.47 |
| 2016 | 15.23 |
| 2017 | |
| 2018 | 13.56 |