| 年度 | 实际值 |
|---|---|
| 1995 | 44.8 |
| 1996 | 44.7 |
| 1997 | 46.7 |
| 1998 | 46.2 |
| 1999 | |
| 2000 | 49 |
| 2001 | 49.32 |
| 2002 | 49.08 |
| 2003 | 55.11 |
| 2004 | 57.28 |
| 2005 | 47.93 |
| 2006 | 47.72 |
| 2007 | 47.38 |
| 2008 | 43.41 |
| 2009 | |
| 2010 | 37.58 |
| 2011 | 41.24 |
| 2012 | 39.01 |
| 2013 | 32.48 |
| 2014 | 28.72 |
| 2015 | 22.34 |
| 2016 | 21.82 |
| 2017 | 21.86 |
| 2018 | 22.02 |