| 年度 | 实际值 |
|---|---|
| 1995 | 30.8 |
| 1996 | 41.2 |
| 1997 | 21.03 |
| 1998 | 35.7 |
| 1999 | 39.1 |
| 2000 | 39.9 |
| 2001 | 40.11 |
| 2002 | 41.4 |
| 2003 | 37.45 |
| 2004 | 37.55 |
| 2005 | 39.07 |
| 2006 | 41.52 |
| 2007 | 38.76 |
| 2008 | 37.73 |
| 2009 | |
| 2010 | 38.34 |
| 2011 | 37.15 |
| 2012 | 46.34 |
| 2013 | 46.75 |
| 2014 | 50.53 |
| 2015 | 47.36 |
| 2016 | 46.81 |
| 2017 | 46.08 |
| 2018 | 44.81 |