| 年度 | 实际值 |
|---|---|
| 1995 | 30.4 |
| 1996 | 30.6 |
| 1997 | 23.61 |
| 1998 | 35.1 |
| 1999 | 38 |
| 2000 | 38.9 |
| 2001 | 40.72 |
| 2002 | 40.65 |
| 2003 | 39.03 |
| 2004 | 37.21 |
| 2005 | 36.42 |
| 2006 | 34.5 |
| 2007 | 33.15 |
| 2008 | 32.2 |
| 2009 | |
| 2010 | 35 |
| 2011 | 34.58 |
| 2012 | 35.83 |
| 2013 | 36.1 |
| 2014 | 36.36 |
| 2015 | 37.83 |
| 2016 | 38.69 |
| 2017 | 40.86 |
| 2018 | 42.04 |