| 年度 | 实际值 |
|---|---|
| 1995 | 29.1 |
| 1996 | 29.3 |
| 1997 | 28.37 |
| 1998 | 35.9 |
| 1999 | 36.1 |
| 2000 | 40.3 |
| 2001 | 40.94 |
| 2002 | 40.03 |
| 2003 | 39.88 |
| 2004 | 37.2 |
| 2005 | 39.4 |
| 2006 | 37.71 |
| 2007 | 39.9 |
| 2008 | 34.44 |
| 2009 | |
| 2010 | 32.79 |
| 2011 | 30.34 |
| 2012 | 31.59 |
| 2013 | 33.31 |
| 2014 | 38.45 |
| 2015 | 44.71 |
| 2016 | 45.73 |
| 2017 | 48.07 |
| 2018 | 49.37 |