| 年度 | 实际值 |
|---|---|
| 1995 | 8.1 |
| 1996 | 7.9 |
| 1997 | 34.08 |
| 1998 | 10.1 |
| 1999 | 10.6 |
| 2000 | 7.9 |
| 2001 | 8.67 |
| 2002 | 13.14 |
| 2003 | 12.12 |
| 2004 | 12.03 |
| 2005 | 12.23 |
| 2006 | 15.54 |
| 2007 | 21.17 |
| 2008 | 20.09 |
| 2009 | |
| 2010 | 22.22 |
| 2011 | 24.39 |
| 2012 | 24.95 |
| 2013 | 25.82 |
| 2014 | 30.25 |
| 2015 | 32.38 |
| 2016 | 35.47 |
| 2017 | 34.7 |
| 2018 | 34.91 |