| 年度 | 实际值 |
|---|---|
| 1995 | 28.7 |
| 1996 | 30.1 |
| 1997 | 32.69 |
| 1998 | 34.5 |
| 1999 | 36 |
| 2000 | 37.2 |
| 2001 | 37.46 |
| 2002 | 37.71 |
| 2003 | 36.58 |
| 2004 | 34.54 |
| 2005 | 31.29 |
| 2006 | 31.98 |
| 2007 | 32.39 |
| 2008 | 32.13 |
| 2009 | |
| 2010 | 34.05 |
| 2011 | 34.85 |
| 2012 | 35.87 |
| 2013 | 36.92 |
| 2014 | 39.58 |
| 2015 | 41.43 |
| 2016 | 43.51 |
| 2017 | |
| 2018 | 44.72 |