| 年度 | 实际值 |
|---|---|
| 1995 | 30.3 |
| 1996 | 29.2 |
| 1997 | 29.85 |
| 1998 | 30.3 |
| 1999 | 31.1 |
| 2000 | 36.7 |
| 2001 | 37.42 |
| 2002 | 40.42 |
| 2003 | 39.65 |
| 2004 | 38.32 |
| 2005 | 34.76 |
| 2006 | 34.13 |
| 2007 | 35.02 |
| 2008 | 34.18 |
| 2009 | |
| 2010 | 36.62 |
| 2011 | 36.12 |
| 2012 | 36.16 |
| 2013 | 35.72 |
| 2014 | 36.24 |
| 2015 | 38.06 |
| 2016 | 39.95 |
| 2017 | |
| 2018 | 41.08 |