| 年度 | 实际值 |
|---|---|
| 1995 | 14.8 |
| 1996 | 12.5 |
| 1997 | 32.29 |
| 1998 | 28.5 |
| 1999 | 26.3 |
| 2000 | 26.9 |
| 2001 | 27.27 |
| 2002 | 25.41 |
| 2003 | 22.74 |
| 2004 | 22.62 |
| 2005 | 23.78 |
| 2006 | 22.5 |
| 2007 | 23.41 |
| 2008 | 21.51 |
| 2009 | |
| 2010 | 14.44 |
| 2011 | 15.29 |
| 2012 | 14.51 |
| 2013 | 14.22 |
| 2014 | 14.49 |
| 2015 | 14.48 |
| 2016 | 14.32 |
| 2017 | |
| 2018 | 12.49 |