| 年度 | 实际值 |
|---|---|
| 2000 | 7.2 |
| 2001 | 7.5 |
| 2002 | 8.7 |
| 2003 | 9.5 |
| 2004 | 16.1 |
| 2005 | 20.7 |
| 2006 | 20.5 |
| 2007 | 25.17581868 |
| 2008 | 10.3591091447106 |
| 2009 | 17.9527786406793 |
| 2010 | 20.1 |
| 2011 | 2.49934123847166 |
| 2012 | 2.30003026524743 |
| 2013 | 8 |
| 2014 | 10 |
| 2015 | 8.20000015999753 |
| 2016 | 8.8 |
| 2017 | 6.9 |
| 2018 | 7.3 |