| 年度 | 实际值 |
|---|---|
| 1995 | 29.8 |
| 1996 | 34.8 |
| 1997 | 36.95 |
| 1998 | 37.4 |
| 1999 | 38.1 |
| 2000 | 36.4 |
| 2001 | 36.46 |
| 2002 | 35.96 |
| 2003 | 36.78 |
| 2004 | 36.82 |
| 2005 | 34.02 |
| 2006 | 35.59 |
| 2007 | 36.77 |
| 2008 | 37.87 |
| 2009 | |
| 2010 | 40.46 |
| 2011 | 42.15 |
| 2012 | 43.98 |
| 2013 | 46.43 |
| 2014 | 48.28 |
| 2015 | 50.4 |
| 2016 | 51.95 |
| 2017 | 51.8 |
| 2018 | 52.22 |