| 年度 | 实际值 |
|---|---|
| 1995 | 25.3 |
| 1996 | 25.5 |
| 1997 | 29.69 |
| 1998 | 30.2 |
| 1999 | 34.2 |
| 2000 | 33.8 |
| 2001 | 34.23 |
| 2002 | 33.74 |
| 2003 | 31.41 |
| 2004 | 27.82 |
| 2005 | 26.81 |
| 2006 | 27.46 |
| 2007 | 27.44 |
| 2008 | 28.42 |
| 2009 | |
| 2010 | 31.28 |
| 2011 | 32.97 |
| 2012 | 33.98 |
| 2013 | 35.14 |
| 2014 | 38.21 |
| 2015 | 39.72 |
| 2016 | 41.19 |
| 2017 | |
| 2018 | 42.7 |