| 年度 | 实际值 |
|---|---|
| 1995 | 20.1 |
| 1996 | 23.1 |
| 1997 | 40.39 |
| 1998 | 28.4 |
| 1999 | 29.4 |
| 2000 | 33.4 |
| 2001 | 32.95 |
| 2002 | 31.71 |
| 2003 | 27.76 |
| 2004 | 22.63 |
| 2005 | 29.99 |
| 2006 | 31.64 |
| 2007 | 30.11 |
| 2008 | 26.86 |
| 2009 | |
| 2010 | 31.18 |
| 2011 | 27.88 |
| 2012 | 30.17 |
| 2013 | 32.77 |
| 2014 | 36.66 |
| 2015 | 43.08 |
| 2016 | 45.23 |
| 2017 | 44.88 |
| 2018 | 46.46 |