| 年度 | 实际值 |
|---|---|
| 1995 | 15.2 |
| 1996 | 23.1 |
| 1997 | 39.98 |
| 1998 | 23.6 |
| 1999 | 27 |
| 2000 | 28 |
| 2001 | 29.9 |
| 2002 | 29.84 |
| 2003 | 29.72 |
| 2004 | 29.14 |
| 2005 | 32.45 |
| 2006 | 29.29 |
| 2007 | 28.03 |
| 2008 | 27.72 |
| 2009 | |
| 2010 | 30.28 |
| 2011 | 29.42 |
| 2012 | 29.53 |
| 2013 | 31.89 |
| 2014 | 34.94 |
| 2015 | 39.78 |
| 2016 | 45.64 |
| 2017 | 46.84 |
| 2018 | 43.79 |