| 年度 | 实际值 |
|---|---|
| 1992 | 18.2 |
| 1993 | |
| 1994 | |
| 1995 | 18 |
| 1996 | |
| 1997 | |
| 1998 | |
| 1999 | 9.8627 |
| 2000 | 9.8818 |
| 2001 | 16.7204 |
| 2002 | 15.0594 |
| 2003 | 13.8681 |
| 2004 | 14.3216 |
| 2005 | 14.2278 |
| 2006 | 13.3115 |
| 2007 | 13.3615 |
| 2008 | 10.2386 |
| 2009 | 10.0985 |
| 2010 | 10.1356 |
| 2011 | 10.1338 |
| 2012 | 17.1755 |
| 2013 | 11.0369 |
| 2014 | 17.2732 |
| 2015 | 17.2307 |