| 年度 | 实际值 |
|---|---|
| 1992 | 8.5 |
| 1993 | |
| 1994 | |
| 1995 | 8.7 |
| 1996 | |
| 1997 | |
| 1998 | |
| 1999 | 9.1609 |
| 2000 | 9.2649 |
| 2001 | 8.6252 |
| 2002 | 8.4887 |
| 2003 | 8.1871 |
| 2004 | 8.2565 |
| 2005 | 8.3545 |
| 2006 | 8.1515 |
| 2007 | 8.8316 |
| 2008 | 6.7018 |
| 2009 | 6.6455 |
| 2010 | 7.3726 |
| 2011 | 7.3518 |
| 2012 | 7.9518 |
| 2013 | 7.9394 |
| 2014 | 8.0775 |
| 2015 | 8.3744 |