| 年度 | 实际值 |
|---|---|
| 1992 | 8.1 |
| 1993 | |
| 1994 | |
| 1995 | 7.9 |
| 1996 | |
| 1997 | |
| 1998 | |
| 1999 | 7.6662 |
| 2000 | 7.4479 |
| 2001 | 7.0869 |
| 2002 | 6.4295 |
| 2003 | 6.692 |
| 2004 | 6.5865 |
| 2005 | 6.6165 |
| 2006 | 6.725 |
| 2007 | 7.016 |
| 2008 | 5.5826 |
| 2009 | 5.6384 |
| 2010 | 6.0091 |
| 2011 | 6.0132 |
| 2012 | 5.7627 |
| 2013 | 5.7416 |
| 2014 | 6.1336 |
| 2015 | 6.1544 |