| 年度 | 实际值 |
|---|---|
| 1993 | 30.2 |
| 1994 | |
| 1995 | 34.8 |
| 1996 | 27.9 |
| 1997 | 26.2 |
| 1998 | 28.8 |
| 1999 | .7 |
| 2000 | 30.6 |
| 2001 | 1.92 |
| 2002 | |
| 2003 | 34.36 |
| 2004 | 32.74 |
| 2005 | 34 |
| 2006 | 32.86 |
| 2007 | 32.86 |
| 2008 | 33.64 |
| 2009 | |
| 2010 | 38.04 |
| 2011 | 38.3 |
| 2012 | 37.65 |
| 2013 | 38.09 |
| 2014 | 38.5 |
| 2015 | 38.7 |
| 2016 | 39.23 |
| 2017 | 40.09 |
| 2018 | 40.02 |