| 年度 | 实际值 |
|---|---|
| 1995 | 45.2 |
| 1996 | 39 |
| 1997 | 24.99 |
| 1998 | |
| 1999 | 21.3 |
| 2000 | 20.8 |
| 2001 | 17.14 |
| 2002 | 17.64 |
| 2003 | 15.46 |
| 2004 | 16.05 |
| 2005 | 16.08 |
| 2006 | 14.28 |
| 2007 | 12.99 |
| 2008 | 14.34 |
| 2009 | |
| 2010 | 13.63 |
| 2011 | 13.32 |
| 2012 | 12.97 |
| 2013 | 12.36 |
| 2014 | 11.93 |
| 2015 | 11.61 |
| 2016 | 11.13 |
| 2017 | 10.6 |
| 2018 | 9.23 |