| 年度 | 实际值 |
|---|---|
| 1993 | 29.1 |
| 1994 | |
| 1995 | 30.5 |
| 1996 | 32.1 |
| 1997 | 32.6 |
| 1998 | 33 |
| 1999 | 33.9 |
| 2000 | 42.6 |
| 2001 | 2.8 |
| 2002 | |
| 2003 | 43.06 |
| 2004 | 40.45 |
| 2005 | 40 |
| 2006 | 39.03 |
| 2007 | 38.78 |
| 2008 | 34.41 |
| 2009 | |
| 2010 | 35.16 |
| 2011 | 39.6 |
| 2012 | 38.51 |
| 2013 | 37.78 |
| 2014 | 37.06 |
| 2015 | 38.68 |
| 2016 | 40.15 |
| 2017 | 40.54 |
| 2018 | 41.02 |