| 年度 | 实际值 |
|---|---|
| 1995 | 37.2 |
| 1996 | 35.8 |
| 1997 | 36.43 |
| 1998 | 38.7 |
| 1999 | 40 |
| 2000 | 40.4 |
| 2001 | 40.88 |
| 2002 | 42.15 |
| 2003 | 42.59 |
| 2004 | 45.24 |
| 2005 | 46.36 |
| 2006 | 47.86 |
| 2007 | 48.55 |
| 2008 | 51.71 |
| 2009 | |
| 2010 | 54.19 |
| 2011 | 56.78 |
| 2012 | 55.54 |
| 2013 | 54.98 |
| 2014 | 53.87 |
| 2015 | 50.13 |
| 2016 | 47.38 |
| 2017 | |
| 2018 | 41.76 |