| 年度 | 实际值 |
|---|---|
| 1992 | 20.5 |
| 1993 | |
| 1994 | |
| 1995 | 21 |
| 1996 | |
| 1997 | |
| 1998 | |
| 1999 | 14.6797 |
| 2000 | 13.8333 |
| 2001 | 21.4148 |
| 2002 | 21.4211 |
| 2003 | 21.4878 |
| 2004 | 21.169 |
| 2005 | 20.9846 |
| 2006 | 20.0563 |
| 2007 | 20.2916 |
| 2008 | 22.9341 |
| 2009 | 18.4 |
| 2010 | 20.1083 |
| 2011 | 20.2333 |
| 2012 | 20.1222 |
| 2013 | 19.514 |
| 2014 | 22.0315 |
| 2015 | 21.7972 |