| 年度 | 实际值 |
|---|---|
| 1995 | 32.2 |
| 1996 | 30.6 |
| 1997 | 34.6 |
| 1998 | 27 |
| 1999 | 29.8 |
| 2000 | 33.4 |
| 2001 | 31.63 |
| 2002 | 32.04 |
| 2003 | 36.03 |
| 2004 | 40.06 |
| 2005 | 38.74 |
| 2006 | 41.35 |
| 2007 | 44.62 |
| 2008 | 48.26 |
| 2009 | |
| 2010 | 50.66 |
| 2011 | 51.25 |
| 2012 | 49.49 |
| 2013 | 49.86 |
| 2014 | 42.57 |
| 2015 | 30.37 |
| 2016 | 24.54 |
| 2017 | |
| 2018 | 28.39 |