| 年度 | 实际值 |
|---|---|
| 1995 | 39.2 |
| 1996 | 38.3 |
| 1997 | 32.1 |
| 1998 | 38.7 |
| 1999 | 40.5 |
| 2000 | 38.5 |
| 2001 | 39.45 |
| 2002 | 38.93 |
| 2003 | 43.81 |
| 2004 | 41.11 |
| 2005 | 38.64 |
| 2006 | 36.58 |
| 2007 | 34.25 |
| 2008 | 32.43 |
| 2009 | |
| 2010 | 32.03 |
| 2011 | 29.36 |
| 2012 | 28.82 |
| 2013 | 29.32 |
| 2014 | 30.32 |
| 2015 | 31.9 |
| 2016 | 32.94 |
| 2017 | 42.08 |
| 2018 | 43.8 |