| 年度 | 实际值 |
|---|---|
| 1995 | 46.7 |
| 1996 | 46.7 |
| 1997 | 46.54 |
| 1998 | 44.9 |
| 1999 | 45.7 |
| 2000 | 43.4 |
| 2001 | 41.89 |
| 2002 | 40.88 |
| 2003 | 43.13 |
| 2004 | 44.16 |
| 2005 | 39.68 |
| 2006 | 40.01 |
| 2007 | 39.48 |
| 2008 | 38.94 |
| 2009 | |
| 2010 | 37.24 |
| 2011 | 36.84 |
| 2012 | 34.84 |
| 2013 | 33.9 |
| 2014 | 33.47 |
| 2015 | 31.64 |
| 2016 | 29.42 |
| 2017 | |
| 2018 | 27.27 |