| 年度 | 实际值 |
|---|---|
| 1995 | 8.3 |
| 1996 | 8.7 |
| 1997 | 5.22 |
| 1998 | 9.4 |
| 1999 | 9.7 |
| 2000 | 10.3 |
| 2001 | 10.27 |
| 2002 | 9.39 |
| 2003 | 18.7 |
| 2004 | 17.53 |
| 2005 | 17.96 |
| 2006 | 17.87 |
| 2007 | 17.92 |
| 2008 | 19.17 |
| 2009 | |
| 2010 | 23.55 |
| 2011 | 21.94 |
| 2012 | 26.44 |
| 2013 | 26.7 |
| 2014 | 34.79 |
| 2015 | 35.59 |
| 2016 | 36.54 |
| 2017 | 32.53 |
| 2018 | 29.54 |