| 年度 | 实际值 |
|---|---|
| 1993 | 19.9 |
| 1994 | |
| 1995 | 29.8 |
| 1996 | 30 |
| 1997 | 31.9 |
| 1998 | 30.7 |
| 1999 | 35.7 |
| 2000 | 35.9 |
| 2001 | 2.4 |
| 2002 | |
| 2003 | 36.21 |
| 2004 | 52.8 |
| 2005 | 37 |
| 2006 | 41.53 |
| 2007 | 37.24 |
| 2008 | 43.15 |
| 2009 | |
| 2010 | 37.83 |
| 2011 | 45.71 |
| 2012 | 45.82 |
| 2013 | 45.96 |
| 2014 | 45.12 |
| 2015 | 43.09 |
| 2016 | 43.28 |
| 2017 | 44.84 |
| 2018 | 44.93 |