| 年度 | 实际值 |
|---|---|
| 1995 | 25.1 |
| 1996 | 27.3 |
| 1997 | 28.86 |
| 1998 | 31.4 |
| 1999 | 32.1 |
| 2000 | 31.4 |
| 2001 | 31.84 |
| 2002 | 30.91 |
| 2003 | 29.25 |
| 2004 | 26.24 |
| 2005 | 26.64 |
| 2006 | 26.45 |
| 2007 | 25.77 |
| 2008 | 23.71 |
| 2009 | |
| 2010 | 26.39 |
| 2011 | 29.47 |
| 2012 | 30.55 |
| 2013 | 31.09 |
| 2014 | 36.19 |
| 2015 | 38.59 |
| 2016 | 41.7 |
| 2017 | |
| 2018 | 45.7 |