| 年度 | 实际值 |
|---|---|
| 1995 | 35.4 |
| 1996 | 34.1 |
| 1997 | 38.54 |
| 1998 | 35 |
| 1999 | 40.4 |
| 2000 | 40.2 |
| 2001 | 48.17 |
| 2002 | 45.96 |
| 2003 | 44.62 |
| 2004 | 41.45 |
| 2005 | 40.66 |
| 2006 | 37.7 |
| 2007 | 35.36 |
| 2008 | 37.13 |
| 2009 | |
| 2010 | 32.33 |
| 2011 | 29.27 |
| 2012 | 28.61 |
| 2013 | 26.93 |
| 2014 | 30.85 |
| 2015 | 35.05 |
| 2016 | 42.42 |
| 2017 | 43.23 |
| 2018 | 50.45 |