| 年度 | 实际值 |
|---|---|
| 1995 | 30.4 |
| 1996 | 29.1 |
| 1997 | 30.19 |
| 1998 | 31.5 |
| 1999 | 33.9 |
| 2000 | 34.8 |
| 2001 | 35.32 |
| 2002 | 35.16 |
| 2003 | 33.74 |
| 2004 | 34.5 |
| 2005 | 36.04 |
| 2006 | 35.19 |
| 2007 | 34.44 |
| 2008 | 33.32 |
| 2009 | |
| 2010 | 32.75 |
| 2011 | 32.66 |
| 2012 | 33.71 |
| 2013 | 35.76 |
| 2014 | 36.8 |
| 2015 | 40.03 |
| 2016 | 40.26 |
| 2017 | |
| 2018 | 45.83 |