| 年度 | 实际值 |
|---|---|
| 1995 | 40 |
| 1996 | 39.6 |
| 1997 | 41.29 |
| 1998 | 38.8 |
| 1999 | 37.3 |
| 2000 | 36.5 |
| 2001 | 38.75 |
| 2002 | 38.76 |
| 2003 | 36.28 |
| 2004 | 34.85 |
| 2005 | 33.07 |
| 2006 | 31.9 |
| 2007 | 30.31 |
| 2008 | 30.29 |
| 2009 | |
| 2010 | 43.89 |
| 2011 | 40.65 |
| 2012 | 45.43 |
| 2013 | 44.92 |
| 2014 | 44.45 |
| 2015 | 46.92 |
| 2016 | 45.93 |
| 2017 | 49.4 |
| 2018 | 52.37 |