| 年度 | 实际值 |
|---|---|
| 1995 | 44.3 |
| 1996 | 44.7 |
| 1997 | 37.76 |
| 1998 | 42.1 |
| 1999 | 41.4 |
| 2000 | 33.6 |
| 2001 | 37.88 |
| 2002 | 38.12 |
| 2003 | 37.23 |
| 2004 | 37.49 |
| 2005 | 37.82 |
| 2006 | 45.37 |
| 2007 | 48.96 |
| 2008 | 52.51 |
| 2009 | |
| 2010 | 53.07 |
| 2011 | 57.91 |
| 2012 | 58.87 |
| 2013 | 58.27 |
| 2014 | 59.07 |
| 2015 | 56.09 |
| 2016 | 54.12 |
| 2017 | 46.11 |
| 2018 | 41.64 |