| 年度 | 实际值 |
|---|---|
| 1992 | 12.3 |
| 1993 | |
| 1994 | |
| 1995 | 12.5 |
| 1996 | |
| 1997 | |
| 1998 | |
| 1999 | 12.6 |
| 2000 | 12.7707 |
| 2001 | 12.6851 |
| 2002 | 12.6578 |
| 2003 | 12.6477 |
| 2004 | 12.5772 |
| 2005 | 12.63 |
| 2006 | 12.63 |
| 2007 | 12.96 |
| 2008 | 12.9638 |
| 2009 | 13.2055 |
| 2010 | 13.2806 |
| 2011 | 13.3685 |
| 2012 | 13.3507 |
| 2013 | 13.4229 |
| 2014 | 12.52 |
| 2015 | 12.5517138963161 |
| 2016 | 13 |
| 2017 | 13 |