| 年度 | 实际值 |
|---|---|
| 1995 | 29.7 |
| 1996 | 30.9 |
| 1997 | 34.13 |
| 1998 | 33.2 |
| 1999 | 38.3 |
| 2000 | 38.5 |
| 2001 | 39.7 |
| 2002 | 38.75 |
| 2003 | 36.26 |
| 2004 | 30.68 |
| 2005 | 31.18 |
| 2006 | 30.95 |
| 2007 | 31.62 |
| 2008 | 32.23 |
| 2009 | |
| 2010 | 32.19 |
| 2011 | 30.21 |
| 2012 | 31.23 |
| 2013 | 33.35 |
| 2014 | 37.02 |
| 2015 | 39.87 |
| 2016 | 42.37 |
| 2017 | |
| 2018 | 43.26 |