| 年度 | 实际值 |
|---|---|
| 1993 | 2.9 |
| 1994 | |
| 1995 | 9 |
| 1996 | 10.9 |
| 1997 | 11 |
| 1998 | 11.2 |
| 1999 | 11.4 |
| 2000 | 11.8 |
| 2001 | 1.01333333333333 |
| 2002 | |
| 2003 | 18.91 |
| 2004 | 36.04 |
| 2005 | 35 |
| 2006 | 36.47 |
| 2007 | 34.91 |
| 2008 | 26.39 |
| 2009 | |
| 2010 | 26.35 |
| 2011 | 25.08 |
| 2012 | 29.35 |
| 2013 | 33.92 |
| 2014 | 35.27 |
| 2015 | 34.49 |
| 2016 | 35.18 |
| 2017 | 36.59 |
| 2018 | 36.94 |