| 年度 | 实际值 |
|---|---|
| 1995 | 30.3 |
| 1996 | 30.9 |
| 1997 | 30.51 |
| 1998 | 31.9 |
| 1999 | 34.6 |
| 2000 | 36.3 |
| 2001 | 39.41 |
| 2002 | 38.79 |
| 2003 | 40.04 |
| 2004 | 39.98 |
| 2005 | 36.29 |
| 2006 | 35.54 |
| 2007 | 33.72 |
| 2008 | 34.11 |
| 2009 | |
| 2010 | 33.89 |
| 2011 | 31.4 |
| 2012 | 31.27 |
| 2013 | 32.2 |
| 2014 | 33.35 |
| 2015 | 34.19 |
| 2016 | 36.83 |
| 2017 | |
| 2018 | 46.58 |