| 年度 | 实际值 |
|---|---|
| 1996 | 6.34 |
| 1997 | 9.59 |
| 1998 | 4.83 |
| 1999 | 6.07 |
| 2000 | 4.26 |
| 2001 | 2.99 |
| 2002 | 3.77 |
| 2003 | 7.96 |
| 2004 | 8.1694 |
| 2005 | 6.89202713901806 |
| 2006 | 8.28504202956301 |
| 2007 | 4.88780250111097 |
| 2008 | 5.95246023454532 |
| 2009 | 9.20161691905527 |
| 2010 | 8.58 |
| 2011 | 10.9 |
| 2012 | 20.3 |
| 2013 | 19.6 |
| 2014 | 15.9 |
| 2015 | 13.06 |
| 2016 | 10.93 |
| 2017 | 4.48 |
| 2018 | 4.8 |