| 年度 | 实际值 |
|---|---|
| 1992 | 13.5 |
| 1993 | |
| 1994 | |
| 1995 | 13.7 |
| 1996 | |
| 1997 | |
| 1998 | |
| 1999 | 14 |
| 2000 | 14.2616 |
| 2001 | 14.2805 |
| 2002 | 14.463 |
| 2003 | 14.7622 |
| 2004 | 14.7628 |
| 2005 | 14.83 |
| 2006 | 14.84 |
| 2007 | 14.86 |
| 2008 | 14.9308742548577 |
| 2009 | 15.028 |
| 2010 | 15.2194 |
| 2011 | 15.3781 |
| 2012 | 15.596 |
| 2013 | 15.8635 |
| 2014 | 15.21 |
| 2015 | 15.4703945111492 |
| 2016 | 16 |
| 2017 | 16 |