| 年度 | 实际值 |
|---|---|
| 1995 | 28.8 |
| 1996 | 42.9 |
| 1997 | 37.58 |
| 1998 | 40.1 |
| 1999 | 44.6 |
| 2000 | 41.9 |
| 2001 | 41.6 |
| 2002 | 40.92 |
| 2003 | 35.08 |
| 2004 | 40.28 |
| 2005 | 32.25 |
| 2006 | 31.7 |
| 2007 | 29.86 |
| 2008 | 30.59 |
| 2009 | |
| 2010 | 27.34 |
| 2011 | 27.25 |
| 2012 | 25.91 |
| 2013 | 25.65 |
| 2014 | 23.3 |
| 2015 | 22.59 |
| 2016 | 21.57 |
| 2017 | |
| 2018 | 17.66 |