| 年度 | 实际值 |
|---|---|
| 1995 | 44.1 |
| 1996 | 42.3 |
| 1997 | 40.8 |
| 1998 | 39.1 |
| 1999 | 38.6 |
| 2000 | 38.1 |
| 2001 | 36.22 |
| 2002 | 34.75 |
| 2003 | 35.81 |
| 2004 | 37.6 |
| 2005 | 29.43 |
| 2006 | 27.84 |
| 2007 | 26.83 |
| 2008 | 25.68 |
| 2009 | |
| 2010 | 24.01 |
| 2011 | 23.09 |
| 2012 | 22.7 |
| 2013 | 22.32 |
| 2014 | 21.31 |
| 2015 | 19.74 |
| 2016 | 19.26 |
| 2017 | |
| 2018 | 18.63 |