| 年度 | 实际值 |
|---|---|
| 1995 | 36.6 |
| 1996 | 39.9 |
| 1997 | 36.81 |
| 1998 | 39.7 |
| 1999 | 39.6 |
| 2000 | 37.7 |
| 2001 | 38.09 |
| 2002 | 37.96 |
| 2003 | 34.25 |
| 2004 | 32.35 |
| 2005 | 36.44 |
| 2006 | 37.57 |
| 2007 | 39.88 |
| 2008 | 42.65 |
| 2009 | |
| 2010 | 44.61 |
| 2011 | 45.25 |
| 2012 | 45.54 |
| 2013 | 47.14 |
| 2014 | 48.71 |
| 2015 | 51.32 |
| 2016 | 52.97 |
| 2017 | 51.7 |
| 2018 | 51.84 |