| 年度 | 实际值 |
|---|---|
| 1993 | 24 |
| 1994 | |
| 1995 | 29 |
| 1996 | 29.7 |
| 1997 | 29.9 |
| 1998 | 30.9 |
| 1999 | 31.5 |
| 2000 | 31 |
| 2001 | 2.14 |
| 2002 | |
| 2003 | 33.88 |
| 2004 | 35.05 |
| 2005 | 42 |
| 2006 | 39.02 |
| 2007 | 42.44 |
| 2008 | 41.87 |
| 2009 | |
| 2010 | 43.02 |
| 2011 | 43.18 |
| 2012 | 43.89 |
| 2013 | 44.4 |
| 2014 | 44.76 |
| 2015 | 44.65 |
| 2016 | 45.08 |
| 2017 | 44.36 |
| 2018 | 45.82 |