| 年度 | 实际值 |
|---|---|
| 1992 | 12.3 |
| 1993 | 10.9 |
| 1994 | |
| 1995 | 17.46 |
| 1996 | 10.38 |
| 1997 | 6.4 |
| 1998 | 4.92 |
| 1999 | 6.61 |
| 2000 | 8.9 |
| 2001 | 5.4 |
| 2002 | 4.42 |
| 2003 | 4.68 |
| 2004 | 5.23 |
| 2005 | 5.37 |
| 2006 | 4.76 |
| 2007 | 5.93 |
| 2008 | 5.77 |
| 2009 | |
| 2010 | 10.01 |
| 2011 | 7.1 |
| 2012 | 7.4 |
| 2013 | 15.4 |
| 2014 | 18.2 |
| 2015 | 12.17 |
| 2016 | 13.99 |
| 2017 | 13.83 |
| 2018 | 18.08 |