| 年度 | 实际值 |
|---|---|
| 1995 | 44.6 |
| 1996 | 49.2 |
| 1997 | 45.69 |
| 1998 | 39.6 |
| 1999 | 43.5 |
| 2000 | 37.3 |
| 2001 | 35.44 |
| 2002 | 34.9 |
| 2003 | 35.21 |
| 2004 | 30.8 |
| 2005 | 32.21 |
| 2006 | 25.04 |
| 2007 | 22.35 |
| 2008 | 22.04 |
| 2009 | |
| 2010 | 18.74 |
| 2011 | 18.17 |
| 2012 | 17.97 |
| 2013 | 16.7 |
| 2014 | 16.71 |
| 2015 | 16.89 |
| 2016 | 15.67 |
| 2017 | |
| 2018 | 19.34 |