| 年度 | 实际值 |
|---|---|
| 1993 | 19.8 |
| 1994 | |
| 1995 | 23.5 |
| 1996 | 25 |
| 1997 | 24 |
| 1998 | 24.5 |
| 1999 | 25.5 |
| 2000 | 24.6 |
| 2001 | 1.6 |
| 2002 | |
| 2003 | 26.15 |
| 2004 | 27.35 |
| 2005 | 29 |
| 2006 | 29.18 |
| 2007 | 31.6 |
| 2008 | 32.08 |
| 2009 | |
| 2010 | 36.4 |
| 2011 | 38.5 |
| 2012 | 41.7 |
| 2013 | 42.73 |
| 2014 | 38.76 |
| 2015 | 40.09 |
| 2016 | 41.02 |
| 2017 | 41.78 |
| 2018 | 42.87 |