| 年度 | 实际值 |
|---|---|
| 1993 | 7.7 |
| 1994 | |
| 1995 | 8.33 |
| 1996 | 8.65 |
| 1997 | 8.36 |
| 1998 | 4.18 |
| 1999 | 7.79 |
| 2000 | 10.96 |
| 2001 | 7.03 |
| 2002 | 8.34 |
| 2003 | 8.9 |
| 2004 | 16.12 |
| 2005 | 8.9 |
| 2006 | 18.85 |
| 2007 | 16.74 |
| 2008 | 15.69 |
| 2009 | |
| 2010 | 27.99 |
| 2011 | 7.6 |
| 2012 | 16.4 |
| 2013 | 18.3 |
| 2014 | 19.4 |
| 2015 | 17.33 |
| 2016 | 14.92 |
| 2017 | 6.5 |
| 2018 | 15.01 |