| 年度 | 实际值 |
|---|---|
| 1995 | 20.8 |
| 1996 | 22.9 |
| 1997 | 24.58 |
| 1998 | 23.2 |
| 1999 | 23.6 |
| 2000 | 22.4 |
| 2001 | 22.54 |
| 2002 | 22.45 |
| 2003 | 21.86 |
| 2004 | 30.82 |
| 2005 | 30.32 |
| 2006 | 32.34 |
| 2007 | 32.34 |
| 2008 | 34.2 |
| 2009 | |
| 2010 | 37.34 |
| 2011 | 43.66 |
| 2012 | 45.38 |
| 2013 | 45.67 |
| 2014 | 47.01 |
| 2015 | 49.76 |
| 2016 | 43.85 |
| 2017 | 50.31 |
| 2018 | 52.61 |