| 年度 | 实际值 |
|---|---|
| 1995 | 42.8 |
| 1996 | 45.8 |
| 1997 | 45.41 |
| 1998 | 43.3 |
| 1999 | 42.8 |
| 2000 | 40.6 |
| 2001 | 39.93 |
| 2002 | 38.81 |
| 2003 | 35.37 |
| 2004 | 30.85 |
| 2005 | 22.15 |
| 2006 | 18.07 |
| 2007 | 14.14 |
| 2008 | 13.33 |
| 2009 | |
| 2010 | 11.03 |
| 2011 | 13.89 |
| 2012 | 14.9 |
| 2013 | 15.34 |
| 2014 | 14.66 |
| 2015 | 15.07 |
| 2016 | 15.4 |
| 2017 | |
| 2018 | 14.78 |