| 年度 | 实际值 |
|---|---|
| 1995 | 29.9 |
| 1996 | 25.8 |
| 1997 | 35.37 |
| 1998 | 33.6 |
| 1999 | 34 |
| 2000 | 33.4 |
| 2001 | 33.03 |
| 2002 | 33.39 |
| 2003 | 34.79 |
| 2004 | 34.44 |
| 2005 | 36.05 |
| 2006 | 35.47 |
| 2007 | 29.61 |
| 2008 | 27.5 |
| 2009 | |
| 2010 | 30.33 |
| 2011 | 26.36 |
| 2012 | 29.19 |
| 2013 | 31.41 |
| 2014 | 39.8 |
| 2015 | 39.6 |
| 2016 | 44.1 |
| 2017 | 52.52 |
| 2018 | 54.98 |