| 年度 | 实际值 |
|---|---|
| 1995 | 42.8 |
| 1996 | 44.2 |
| 1997 | 44.55 |
| 1998 | 41.5 |
| 1999 | 40.1 |
| 2000 | 38.4 |
| 2001 | 36.55 |
| 2002 | 34.63 |
| 2003 | 32.74 |
| 2004 | 30.44 |
| 2005 | 27.14 |
| 2006 | 25.84 |
| 2007 | 25.11 |
| 2008 | 23.87 |
| 2009 | |
| 2010 | 21.92 |
| 2011 | 20.91 |
| 2012 | 19.84 |
| 2013 | 18.55 |
| 2014 | 16.51 |
| 2015 | 16.43 |
| 2016 | 17.24 |
| 2017 | |
| 2018 | 16.24 |