| 年度 | 实际值 |
|---|---|
| 1995 | 25.5 |
| 1996 | 24.5 |
| 1997 | 26.1 |
| 1998 | 27.8 |
| 1999 | 29.5 |
| 2000 | 30.4 |
| 2001 | 33.54 |
| 2002 | 34.38 |
| 2003 | 35.59 |
| 2004 | 34.13 |
| 2005 | 33.49 |
| 2006 | 33.62 |
| 2007 | 33.73 |
| 2008 | 32.61 |
| 2009 | |
| 2010 | 35.28 |
| 2011 | 34.63 |
| 2012 | 35.69 |
| 2013 | 37.03 |
| 2014 | 38.91 |
| 2015 | 41.21 |
| 2016 | 44.46 |
| 2017 | |
| 2018 | 51.88 |