| 年度 | 实际值 |
|---|---|
| 1993 | 4.4 |
| 1994 | |
| 1995 | 17.9 |
| 1996 | 19 |
| 1997 | |
| 1998 | |
| 1999 | |
| 2000 | 13.9 |
| 2001 | .926666666666667 |
| 2002 | |
| 2003 | 30.74 |
| 2004 | 32.93 |
| 2005 | 33 |
| 2006 | 37.33 |
| 2007 | 38.44 |
| 2008 | 35.79 |
| 2009 | |
| 2010 | 55.17 |
| 2011 | 32.63 |
| 2012 | 37.92 |
| 2013 | 40.54 |
| 2014 | 39.95 |
| 2015 | 43.58 |
| 2016 | 40.44 |
| 2017 | 39.62 |
| 2018 | 39.98 |