| 年度 | 实际值 |
|---|---|
| 1995 | 32.3 |
| 1996 | 34.7 |
| 1997 | 33.18 |
| 1998 | 34.9 |
| 1999 | 35.3 |
| 2000 | 30.1 |
| 2001 | 30.13 |
| 2002 | 30.66 |
| 2003 | 29.08 |
| 2004 | 29.21 |
| 2005 | 28.56 |
| 2006 | 30.4 |
| 2007 | 31.41 |
| 2008 | 33.38 |
| 2009 | |
| 2010 | 40.49 |
| 2011 | 43.31 |
| 2012 | 44.96 |
| 2013 | 44.98 |
| 2014 | 44.03 |
| 2015 | 42.11 |
| 2016 | 39.76 |
| 2017 | |
| 2018 | 38.08 |