| 年度 | 实际值 |
|---|---|
| 1995 | 34.2 |
| 1996 | 31.1 |
| 1997 | 37.07 |
| 1998 | 26.7 |
| 1999 | 32.8 |
| 2000 | 32.1 |
| 2001 | 31.94 |
| 2002 | 32.6 |
| 2003 | 33.32 |
| 2004 | 30.59 |
| 2005 | 34.13 |
| 2006 | 36.39 |
| 2007 | 38.63 |
| 2008 | 35.54 |
| 2009 | |
| 2010 | 44.55 |
| 2011 | 43.01 |
| 2012 | 42.75 |
| 2013 | 53.27 |
| 2014 | 49.59 |
| 2015 | 53.45 |
| 2016 | 54.52 |
| 2017 | 56.27 |
| 2018 | 57.86 |