| 年度 | 实际值 |
|---|---|
| 1992 | 7.5 |
| 1993 | 7.7 |
| 1994 | |
| 1995 | 6.25 |
| 1996 | 6.31 |
| 1997 | 5.92 |
| 1998 | 6.09 |
| 1999 | 6.23 |
| 2000 | 4.51 |
| 2001 | 4.2 |
| 2002 | 3.09 |
| 2003 | 2.24 |
| 2004 | 3.82 |
| 2005 | 3.18 |
| 2006 | 3.51 |
| 2007 | 3.72 |
| 2008 | 4.43 |
| 2009 | |
| 2010 | 6.72 |
| 2011 | 5.3 |
| 2012 | 6.2 |
| 2013 | 8.5 |
| 2014 | 8 |
| 2015 | 12.02 |
| 2016 | 10.35 |
| 2017 | 15.59 |
| 2018 | 12.8 |