| 年度 | 实际值 |
|---|---|
| 1995 | 29.2 |
| 1996 | 29.1 |
| 1997 | 28.33 |
| 1998 | 28.6 |
| 1999 | 29.1 |
| 2000 | 29.9 |
| 2001 | 31.66 |
| 2002 | 32.22 |
| 2003 | 32.29 |
| 2004 | 31.61 |
| 2005 | 35.61 |
| 2006 | 35.96 |
| 2007 | 35.74 |
| 2008 | 35.59 |
| 2009 | |
| 2010 | 35.62 |
| 2011 | 34.89 |
| 2012 | 34.06 |
| 2013 | 32.04 |
| 2014 | 35.45 |
| 2015 | 38.45 |
| 2016 | 41.78 |
| 2017 | |
| 2018 | 49.4 |