| 年度 | 实际值 |
|---|---|
| 1995 | 39.7 |
| 1996 | 42.1 |
| 1997 | 35.49 |
| 1998 | 46.3 |
| 1999 | 46.6 |
| 2000 | 51 |
| 2001 | 51.6 |
| 2002 | 54.08 |
| 2003 | 52.96 |
| 2004 | 51.07 |
| 2005 | 48.99 |
| 2006 | 47.53 |
| 2007 | 48.24 |
| 2008 | 46.58 |
| 2009 | |
| 2010 | 50.21 |
| 2011 | 48.12 |
| 2012 | 47.69 |
| 2013 | 49.03 |
| 2014 | 49.61 |
| 2015 | 51.44 |
| 2016 | 52.82 |
| 2017 | 52.78 |
| 2018 | 52.55 |