| 年度 | 实际值 |
|---|---|
| 1995 | 29.6 |
| 1996 | 29.4 |
| 1997 | 30.44 |
| 1998 | 30.9 |
| 1999 | 32.1 |
| 2000 | 33.8 |
| 2001 | 35.13 |
| 2002 | 35.96 |
| 2003 | 35.33 |
| 2004 | 32.57 |
| 2005 | 30.66 |
| 2006 | 30.24 |
| 2007 | 30.73 |
| 2008 | 31.09 |
| 2009 | |
| 2010 | 33.44 |
| 2011 | 34.94 |
| 2012 | 36.33 |
| 2013 | 37.72 |
| 2014 | 39.91 |
| 2015 | 41.6 |
| 2016 | 43.27 |
| 2017 | |
| 2018 | 44.41 |