| 年度 | 实际值 |
|---|---|
| 1995 | 39.7 |
| 1996 | 36 |
| 1997 | 47.82 |
| 1998 | 33.7 |
| 1999 | 32.3 |
| 2000 | 32.6 |
| 2001 | 34.07 |
| 2002 | 34.68 |
| 2003 | 34.88 |
| 2004 | 33.14 |
| 2005 | 35.31 |
| 2006 | 34.69 |
| 2007 | 31.43 |
| 2008 | 29.63 |
| 2009 | |
| 2010 | 35.16 |
| 2011 | 29.73 |
| 2012 | 30.46 |
| 2013 | 30.85 |
| 2014 | 33.21 |
| 2015 | 34.41 |
| 2016 | 35.41 |
| 2017 | 40.81 |
| 2018 | 43.28 |