| 年度 | 实际值 |
|---|---|
| 1992 | 15.4 |
| 1993 | |
| 1994 | |
| 1995 | 15.4 |
| 1996 | |
| 1997 | |
| 1998 | |
| 1999 | 15.3 |
| 2000 | 16.15 |
| 2001 | 15.5 |
| 2002 | 15.4747 |
| 2003 | 15.5426 |
| 2004 | 15.5432 |
| 2005 | 15.51 |
| 2006 | 15.5 |
| 2007 | 15.54 |
| 2008 | 15.57 |
| 2009 | 15.359 |
| 2010 | 15.5194 |
| 2011 | 15.7135 |
| 2012 | 15.8555 |
| 2013 | 16.0453 |
| 2014 | 15.43 |
| 2015 | 15.47 |
| 2016 | 16 |
| 2017 | 16 |