| 年度 | 实际值 |
|---|---|
| 1995 | 25.4 |
| 1996 | 27.7 |
| 1997 | 44.45 |
| 1998 | 33 |
| 1999 | 36 |
| 2000 | 36.9 |
| 2001 | 38.14 |
| 2002 | 37.17 |
| 2003 | 35.19 |
| 2004 | 31.94 |
| 2005 | 26.09 |
| 2006 | 24.55 |
| 2007 | 25.06 |
| 2008 | 22.17 |
| 2009 | |
| 2010 | 24.28 |
| 2011 | 23.89 |
| 2012 | 32.68 |
| 2013 | 36.1 |
| 2014 | 41.42 |
| 2015 | 43.74 |
| 2016 | 46.39 |
| 2017 | 47.07 |
| 2018 | 46.69 |