| 年度 | 实际值 |
|---|---|
| 1995 | 30.8 |
| 1996 | 31.8 |
| 1997 | 31.58 |
| 1998 | 33.5 |
| 1999 | 33.9 |
| 2000 | 35 |
| 2001 | 35.74 |
| 2002 | 36.41 |
| 2003 | 36.32 |
| 2004 | 34.99 |
| 2005 | 32.91 |
| 2006 | 33.72 |
| 2007 | 34.65 |
| 2008 | 36.07 |
| 2009 | |
| 2010 | 33.59 |
| 2011 | 31.36 |
| 2012 | 31.12 |
| 2013 | 31.54 |
| 2014 | 34.48 |
| 2015 | 38.2 |
| 2016 | 38.61 |
| 2017 | |
| 2018 | 46.27 |