| 年度 | 实际值 |
|---|---|
| 1995 | 35.8 |
| 1996 | 25.7 |
| 1997 | 16.67 |
| 1998 | 24 |
| 1999 | 25.9 |
| 2000 | 26.2 |
| 2001 | 27.75 |
| 2002 | 28.31 |
| 2003 | 31.42 |
| 2004 | 29.97 |
| 2005 | 39.04 |
| 2006 | 38.3 |
| 2007 | 41.59 |
| 2008 | 43.46 |
| 2009 | |
| 2010 | 44.05 |
| 2011 | 43.61 |
| 2012 | 34.99 |
| 2013 | 34.8 |
| 2014 | 32.93 |
| 2015 | 35.1 |
| 2016 | 35.76 |
| 2017 | 38.61 |
| 2018 | 41.01 |