| 年度 | 实际值 |
|---|---|
| 1993 | 12.4 |
| 1994 | |
| 1995 | 13.2 |
| 1996 | 13.2 |
| 1997 | 12.8 |
| 1998 | 13 |
| 1999 | 13.1 |
| 2000 | 12.8 |
| 2001 | 1.04666666666667 |
| 2002 | |
| 2003 | 27.84 |
| 2004 | 27.09 |
| 2005 | 44 |
| 2006 | 45.09 |
| 2007 | 46.09 |
| 2008 | 47.11 |
| 2009 | |
| 2010 | 48.13 |
| 2011 | 45.14 |
| 2012 | 45.24 |
| 2013 | 45.56 |
| 2014 | 46.08 |
| 2015 | 46.47 |
| 2016 | 46.97 |
| 2017 | 47.18 |
| 2018 | 47.31 |