| 年度 | 实际值 |
|---|---|
| 1992 | 5.1 |
| 1993 | 5.6 |
| 1994 | |
| 1995 | 4.93 |
| 1996 | 5.76 |
| 1997 | 7.49 |
| 1998 | 6.15 |
| 1999 | 6.62 |
| 2000 | 7.82 |
| 2001 | 8.68 |
| 2002 | 6.97 |
| 2003 | 8.49 |
| 2004 | 9.65 |
| 2005 | 3.96 |
| 2006 | 12.21 |
| 2007 | 11.26 |
| 2008 | 9.74 |
| 2009 | |
| 2010 | 12 |
| 2011 | 11.3 |
| 2012 | 10 |
| 2013 | 9.9 |
| 2014 | 11.4 |
| 2015 | 11.11 |
| 2016 | 9.98 |
| 2017 | 7.66 |
| 2018 | 6.83 |