| 年度 | 实际值 |
|---|---|
| 1992 | 12.5 |
| 1993 | 12.9 |
| 1994 | |
| 1995 | 10.05 |
| 1996 | 9.78 |
| 1997 | 9.99 |
| 1998 | 5.53 |
| 1999 | 8.46 |
| 2000 | 5.62 |
| 2001 | 4.62 |
| 2002 | 3.28 |
| 2003 | 3.56 |
| 2004 | 4.68 |
| 2005 | 4.58 |
| 2006 | 4.04 |
| 2007 | 3.96 |
| 2008 | 4.69 |
| 2009 | |
| 2010 | 4.53 |
| 2011 | 6 |
| 2012 | 5.8 |
| 2013 | 6.6 |
| 2014 | 6.6 |
| 2015 | 6.72 |
| 2016 | 10.04 |
| 2017 | 16.97 |
| 2018 | 12.6 |