| 年度 | 实际值 |
|---|---|
| 1995 | 34.3 |
| 1996 | 35 |
| 1997 | 41.85 |
| 1998 | 38.2 |
| 1999 | 36.6 |
| 2000 | 36.9 |
| 2001 | 36.18 |
| 2002 | 30.37 |
| 2003 | 29.01 |
| 2004 | 24.25 |
| 2005 | 28.97 |
| 2006 | 23.79 |
| 2007 | 18.16 |
| 2008 | 14.79 |
| 2009 | |
| 2010 | 26.11 |
| 2011 | 24.02 |
| 2012 | 23.05 |
| 2013 | 25.35 |
| 2014 | 27.69 |
| 2015 | 32.06 |
| 2016 | 33.53 |
| 2017 | |
| 2018 | 31.18 |