| 年度 | 实际值 |
|---|---|
| 1995 | 31.4 |
| 1996 | 13.7 |
| 1997 | 11.7 |
| 1998 | 6.2 |
| 1999 | 4.53 |
| 2000 | 2.7 |
| 2001 | 3.7 |
| 2002 | 5.9 |
| 2003 | 8.8 |
| 2004 | 11.1 |
| 2005 | 11.4 |
| 2006 | 11.7 |
| 2007 | 12.9884494410577 |
| 2008 | 10.536481418887 |
| 2009 | 10.7 |
| 2010 | 13.9 |
| 2011 | 11.9423750399703 |
| 2012 | 9.6 |
| 2013 | 9.9 |
| 2014 | 9.1 |
| 2015 | 8.4 |
| 2016 | |
| 2017 | 8.6 |
| 2018 | 6.9 |