| 年度 | 实际值 |
|---|---|
| 1995 | 32.6 |
| 1996 | 31.2 |
| 1997 | 33.16 |
| 1998 | 33.4 |
| 1999 | 33.7 |
| 2000 | 34.3 |
| 2001 | 36.18 |
| 2002 | 36.36 |
| 2003 | 36.83 |
| 2004 | 37.85 |
| 2005 | 35.65 |
| 2006 | 34.29 |
| 2007 | 35.1 |
| 2008 | 35.58 |
| 2009 | |
| 2010 | 37.47 |
| 2011 | 38.37 |
| 2012 | 37.99 |
| 2013 | 37.1 |
| 2014 | 38.02 |
| 2015 | 39.73 |
| 2016 | 41.32 |
| 2017 | |
| 2018 | 44.29 |