| 年度 | 实际值 |
|---|---|
| 1995 | 33.4 |
| 1996 | 33.9 |
| 1997 | 39.85 |
| 1998 | 36.4 |
| 1999 | 44.7 |
| 2000 | 42 |
| 2001 | 41.99 |
| 2002 | 40.79 |
| 2003 | 38.96 |
| 2004 | 37.82 |
| 2005 | 37.18 |
| 2006 | 37.73 |
| 2007 | 33.5 |
| 2008 | 34.35 |
| 2009 | |
| 2010 | 34.35 |
| 2011 | 40.55 |
| 2012 | 40.62 |
| 2013 | 40.69 |
| 2014 | 44.19 |
| 2015 | 45.28 |
| 2016 | 46.97 |
| 2017 | 46.77 |
| 2018 | 47.45 |