| 年度 | 实际值 |
|---|---|
| 1995 | 26.4 |
| 1996 | 27.9 |
| 1997 | 28.81 |
| 1998 | 34.9 |
| 1999 | 36.1 |
| 2000 | 35.5 |
| 2001 | 36.1 |
| 2002 | 35.61 |
| 2003 | 34.33 |
| 2004 | 32.61 |
| 2005 | 32.88 |
| 2006 | 31.45 |
| 2007 | 29.27 |
| 2008 | 26.3 |
| 2009 | |
| 2010 | 22.94 |
| 2011 | 21.17 |
| 2012 | 20.93 |
| 2013 | 21.67 |
| 2014 | 22.75 |
| 2015 | 24.17 |
| 2016 | 27.09 |
| 2017 | |
| 2018 | 41.2 |