| 年度 | 实际值 |
|---|---|
| 1992 | 2.3 |
| 1993 | |
| 1994 | |
| 1995 | 2.5 |
| 1996 | |
| 1997 | |
| 1998 | |
| 1999 | 2.4021 |
| 2000 | 2.2547 |
| 2001 | 2.4478 |
| 2002 | 2.3415 |
| 2003 | 2.4396 |
| 2004 | 2.4228 |
| 2005 | 2.3383 |
| 2006 | 2.2814 |
| 2007 | 2.1929 |
| 2008 | 2.1929 |
| 2009 | 1.9972 |
| 2010 | 2.1715 |
| 2011 | 2.1148 |
| 2012 | 2.1269 |
| 2013 | 2.0762 |
| 2014 | 1.9526 |
| 2015 | 1.9552 |