| 年度 | 实际值 |
|---|---|
| 1995 | 32.6 |
| 1996 | 30.7 |
| 1997 | 33.23 |
| 1998 | 31.3 |
| 1999 | 31.8 |
| 2000 | 33.4 |
| 2001 | 32.33 |
| 2002 | 33.16 |
| 2003 | 37.02 |
| 2004 | 39.87 |
| 2005 | 36.87 |
| 2006 | 41.19 |
| 2007 | 47.46 |
| 2008 | 49.87 |
| 2009 | |
| 2010 | 51.24 |
| 2011 | 53.63 |
| 2012 | 55.37 |
| 2013 | 50.87 |
| 2014 | 48.34 |
| 2015 | 47.42 |
| 2016 | 47 |
| 2017 | |
| 2018 | 30.76 |