| 年度 | 实际值 |
|---|---|
| 1995 | 23.9 |
| 1996 | 23.9 |
| 1997 | 23.71 |
| 1998 | 23.7 |
| 1999 | 24.6 |
| 2000 | 24.7 |
| 2001 | 24.71 |
| 2002 | 25.12 |
| 2003 | 24.33 |
| 2004 | 23.48 |
| 2005 | 23.7 |
| 2006 | 24.52 |
| 2007 | 26.12 |
| 2008 | 26.64 |
| 2009 | |
| 2010 | 27.39 |
| 2011 | 28.13 |
| 2012 | 29.74 |
| 2013 | 31.38 |
| 2014 | 35.98 |
| 2015 | 38.25 |
| 2016 | 39.65 |
| 2017 | |
| 2018 | 43.95 |