| 年度 | 实际值 |
|---|---|
| 1995 | 32.5 |
| 1996 | 32.9 |
| 1997 | 29.52 |
| 1998 | 36.9 |
| 1999 | 37.5 |
| 2000 | 40.4 |
| 2001 | 42.04 |
| 2002 | 42.44 |
| 2003 | 42.29 |
| 2004 | 31.66 |
| 2005 | 32.12 |
| 2006 | 32.5 |
| 2007 | 32.07 |
| 2008 | 32.14 |
| 2009 | |
| 2010 | 37.12 |
| 2011 | 33.09 |
| 2012 | 33.36 |
| 2013 | 35.18 |
| 2014 | 35.62 |
| 2015 | 38.18 |
| 2016 | 40.25 |
| 2017 | 43.83 |
| 2018 | 44.71 |