| 年度 | 实际值 |
|---|---|
| 1992 | 9 |
| 1993 | 10.8 |
| 1994 | |
| 1995 | 10.71 |
| 1996 | 10.4 |
| 1997 | 10.14 |
| 1998 | 5.74 |
| 1999 | 9.52 |
| 2000 | 10.04 |
| 2001 | 8.12 |
| 2002 | 7.8 |
| 2003 | 7.55 |
| 2004 | 8.35 |
| 2005 | 8.4 |
| 2006 | 11.25 |
| 2007 | 10.57 |
| 2008 | 9.11 |
| 2009 | |
| 2010 | 10.78 |
| 2011 | 11 |
| 2012 | 11.3 |
| 2013 | 11.1 |
| 2014 | 10.4 |
| 2015 | 18.39 |
| 2016 | 18.92 |
| 2017 | 10.99 |
| 2018 | 2.62 |