| 年度 | 实际值 |
|---|---|
| 1995 | 45.2 |
| 1996 | 40.2 |
| 1997 | 40.42 |
| 1998 | 40 |
| 1999 | 39.2 |
| 2000 | 37.1 |
| 2001 | 36.19 |
| 2002 | 35.93 |
| 2003 | 36.3 |
| 2004 | 38.19 |
| 2005 | 37.01 |
| 2006 | 34.13 |
| 2007 | 36.48 |
| 2008 | 37.92 |
| 2009 | |
| 2010 | 39.17 |
| 2011 | 37.31 |
| 2012 | 37.84 |
| 2013 | 38.72 |
| 2014 | 33.52 |
| 2015 | 38 |
| 2016 | 37.21 |
| 2017 | 35.33 |
| 2018 | 33.64 |