| 年度 | 实际值 |
|---|---|
| 1995 | 53.2 |
| 1996 | 50.2 |
| 1997 | 49.56 |
| 1998 | 47.2 |
| 1999 | 47.8 |
| 2000 | 49.3 |
| 2001 | 48.32 |
| 2002 | 48.75 |
| 2003 | 43.79 |
| 2004 | 45.65 |
| 2005 | 37.74 |
| 2006 | 37.69 |
| 2007 | 37.17 |
| 2008 | 36.71 |
| 2009 | |
| 2010 | 39.25 |
| 2011 | 37.83 |
| 2012 | 33.81 |
| 2013 | 32.57 |
| 2014 | 23.48 |
| 2015 | 18.67 |
| 2016 | 19.7 |
| 2017 | |
| 2018 | 21.64 |