| 年度 | 实际值 |
|---|---|
| 1995 | 31.6 |
| 1996 | 28.9 |
| 1997 | 44.18 |
| 1998 | 29 |
| 1999 | 29.5 |
| 2000 | 30.6 |
| 2001 | 33.96 |
| 2002 | 35.08 |
| 2003 | 37.28 |
| 2004 | 36.42 |
| 2005 | 36.98 |
| 2006 | 35.24 |
| 2007 | 36.08 |
| 2008 | 35.77 |
| 2009 | |
| 2010 | 38.36 |
| 2011 | 39.9 |
| 2012 | 40.62 |
| 2013 | 41.63 |
| 2014 | 45.95 |
| 2015 | 47.96 |
| 2016 | 49.68 |
| 2017 | 50.75 |
| 2018 | 51.84 |