| 年度 | 实际值 |
|---|---|
| 1995 | 27.2 |
| 1996 | 28.7 |
| 1997 | 30.89 |
| 1998 | 35.1 |
| 1999 | 36.3 |
| 2000 | 39.6 |
| 2001 | 40.01 |
| 2002 | 39.03 |
| 2003 | 38.49 |
| 2004 | 35.49 |
| 2005 | 35.63 |
| 2006 | 34.86 |
| 2007 | 35.35 |
| 2008 | 30.21 |
| 2009 | |
| 2010 | 27.8 |
| 2011 | 27.09 |
| 2012 | 28.16 |
| 2013 | 29.87 |
| 2014 | 33.78 |
| 2015 | 39.53 |
| 2016 | 40.55 |
| 2017 | |
| 2018 | 42.63 |