| 年度 | 实际值 |
|---|---|
| 1995 | 28.9 |
| 1996 | 30.1 |
| 1997 | 32.55 |
| 1998 | 33 |
| 1999 | 27.9 |
| 2000 | 27.6 |
| 2001 | 27.47 |
| 2002 | 24.89 |
| 2003 | 26.72 |
| 2004 | 25.67 |
| 2005 | 24.42 |
| 2006 | 23.48 |
| 2007 | 23.09 |
| 2008 | 24.09 |
| 2009 | |
| 2010 | 26.45 |
| 2011 | 28.14 |
| 2012 | 29.44 |
| 2013 | 29.24 |
| 2014 | 35.8 |
| 2015 | 35.19 |
| 2016 | 34.28 |
| 2017 | |
| 2018 | 30.03 |