| 年度 | 实际值 |
|---|---|
| 1995 | 35.9 |
| 1996 | 36.3 |
| 1997 | 35.46 |
| 1998 | 35.9 |
| 1999 | 37.5 |
| 2000 | 38 |
| 2001 | 37.07 |
| 2002 | 37.26 |
| 2003 | 42.61 |
| 2004 | 44.43 |
| 2005 | 45.1 |
| 2006 | 46.84 |
| 2007 | 46.39 |
| 2008 | 46.81 |
| 2009 | |
| 2010 | 41.11 |
| 2011 | 41.78 |
| 2012 | 38.87 |
| 2013 | 39.53 |
| 2014 | 39.58 |
| 2015 | 38.15 |
| 2016 | 38.15 |
| 2017 | |
| 2018 | 36.12 |