| 年度 | 实际值 |
|---|---|
| 1995 | 38.9 |
| 1996 | 46.1 |
| 1997 | 46.27 |
| 1998 | 39.6 |
| 1999 | |
| 2000 | 39.5 |
| 2001 | 42.63 |
| 2002 | 42.43 |
| 2003 | 44.22 |
| 2004 | 31.34 |
| 2005 | 31.59 |
| 2006 | 38.66 |
| 2007 | 39.7 |
| 2008 | 42.38 |
| 2009 | |
| 2010 | 34.04 |
| 2011 | 40.23 |
| 2012 | 40.11 |
| 2013 | 38.8 |
| 2014 | 29.14 |
| 2015 | 26.58 |
| 2016 | 25.89 |
| 2017 | 31.45 |
| 2018 | 30.73 |