| 年度 | 实际值 |
|---|---|
| 1995 | 10.4 |
| 1996 | 10.5 |
| 1997 | 11.9 |
| 1998 | 13.5 |
| 1999 | 14.7 |
| 2000 | 11.9 |
| 2001 | 12.87 |
| 2002 | 16.65 |
| 2003 | 15.16 |
| 2004 | 14.45 |
| 2005 | 13.59 |
| 2006 | 15.65 |
| 2007 | 20.12 |
| 2008 | 20.05 |
| 2009 | |
| 2010 | 23.74 |
| 2011 | 24.75 |
| 2012 | 25.67 |
| 2013 | 26.91 |
| 2014 | 30.02 |
| 2015 | 31.94 |
| 2016 | 34.33 |
| 2017 | |
| 2018 | 34.26 |