| 年度 | 实际值 |
|---|---|
| 1995 | 29.6 |
| 1996 | 30.7 |
| 1997 | 31.16 |
| 1998 | 30.9 |
| 1999 | 31.2 |
| 2000 | 31.1 |
| 2001 | 30.74 |
| 2002 | 30.73 |
| 2003 | 30.28 |
| 2004 | 30.87 |
| 2005 | 29.69 |
| 2006 | 29.46 |
| 2007 | 30.17 |
| 2008 | 31.06 |
| 2009 | |
| 2010 | 34.77 |
| 2011 | 34.85 |
| 2012 | 34.96 |
| 2013 | 37.16 |
| 2014 | 42.5 |
| 2015 | 47.1 |
| 2016 | 48.6 |
| 2017 | |
| 2018 | 57.06 |