| 年度 | 实际值 |
|---|---|
| 1995 | 31.2 |
| 1996 | 34.4 |
| 1997 | 35.68 |
| 1998 | 35.6 |
| 1999 | 37.4 |
| 2000 | 39.7 |
| 2001 | 40.42 |
| 2002 | 40.97 |
| 2003 | 37.38 |
| 2004 | 34.53 |
| 2005 | 34.39 |
| 2006 | 33.25 |
| 2007 | 32.19 |
| 2008 | 30.94 |
| 2009 | |
| 2010 | 32.66 |
| 2011 | 32.02 |
| 2012 | 33.94 |
| 2013 | 35.1 |
| 2014 | 39.77 |
| 2015 | 42.81 |
| 2016 | 47.7 |
| 2017 | |
| 2018 | 48.46 |