| 年度 | 实际值 |
|---|---|
| 1992 | 6.6 |
| 1993 | 8.3 |
| 1994 | |
| 1995 | 8.01 |
| 1996 | 11.24 |
| 1997 | 7.75 |
| 1998 | 5.32 |
| 1999 | 8.37 |
| 2000 | 10.64 |
| 2001 | 6.67 |
| 2002 | 5.58 |
| 2003 | 4.73 |
| 2004 | 4.67 |
| 2005 | 5.45 |
| 2006 | 5.64 |
| 2007 | 7.46 |
| 2008 | 9.64 |
| 2009 | |
| 2010 | 8.13 |
| 2011 | 5.8 |
| 2012 | 8.1 |
| 2013 | 14.3 |
| 2014 | 16.3 |
| 2015 | 11.92 |
| 2016 | 12.43 |
| 2017 | 12.73 |
| 2018 | 13.21 |