| 年度 | 实际值 |
|---|---|
| 1995 | 41.1 |
| 1996 | 40 |
| 1997 | 37.55 |
| 1998 | 48.7 |
| 1999 | |
| 2000 | 54.6 |
| 2001 | 43.59 |
| 2002 | 44.48 |
| 2003 | 45.23 |
| 2004 | 44.18 |
| 2005 | 31.49 |
| 2006 | 33.44 |
| 2007 | 36.44 |
| 2008 | 36.24 |
| 2009 | |
| 2010 | 35.94 |
| 2011 | 31.25 |
| 2012 | 30.16 |
| 2013 | 32.52 |
| 2014 | 27.52 |
| 2015 | 27.14 |
| 2016 | 27.61 |
| 2017 | 28.15 |
| 2018 | 29.01 |