| 年度 | 实际值 |
|---|---|
| 1992 | 2.6 |
| 1993 | 3 |
| 1994 | 3 |
| 1995 | 2.7 |
| 1996 | |
| 1997 | |
| 1998 | |
| 1999 | 2.9007 |
| 2000 | 2.8732 |
| 2001 | 2.8802 |
| 2002 | 3.0003 |
| 2003 | 3.1703 |
| 2004 | 3.145 |
| 2005 | 3.1859 |
| 2006 | 3.2438 |
| 2007 | 3.2127 |
| 2008 | 3.6979 |
| 2009 | 4.1746 |
| 2010 | 4.3721 |
| 2011 | 4.2202 |
| 2012 | 4.6505 |
| 2013 | 4.2041 |
| 2014 | 4.2089 |
| 2015 | 4.9508 |