| 年度 | 实际值 |
|---|---|
| 1995 | 35.2 |
| 1996 | 28.1 |
| 1997 | 35.22 |
| 1998 | 35.4 |
| 1999 | 26.5 |
| 2000 | 31 |
| 2001 | 32.45 |
| 2002 | 32.52 |
| 2003 | 34.47 |
| 2004 | 33.72 |
| 2005 | 39.86 |
| 2006 | 40.03 |
| 2007 | 39.02 |
| 2008 | 37.22 |
| 2009 | |
| 2010 | 34.18 |
| 2011 | 32.49 |
| 2012 | 32.24 |
| 2013 | 32.39 |
| 2014 | 32.89 |
| 2015 | 36.17 |
| 2016 | 37.39 |
| 2017 | |
| 2018 | 44.12 |