| 年度 | 实际值 |
|---|---|
| 1992 | 12.4 |
| 1993 | 13.3 |
| 1994 | |
| 1995 | 12.73 |
| 1996 | 14.79 |
| 1997 | 13.91 |
| 1998 | 5.24 |
| 1999 | 16.64 |
| 2000 | 19.17 |
| 2001 | 6.31 |
| 2002 | 7.95 |
| 2003 | 5.67 |
| 2004 | 5.51 |
| 2005 | 2.61 |
| 2006 | 8.01 |
| 2007 | 9.04 |
| 2008 | 6.85 |
| 2009 | |
| 2010 | 8.96 |
| 2011 | 6.9 |
| 2012 | 8.3 |
| 2013 | 8.2 |
| 2014 | 10.4 |
| 2015 | 8.9 |
| 2016 | 9.89 |
| 2017 | 10.52 |
| 2018 | 13.32 |