| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 21.2 | 30 |
| 2015 | 21.2 | 30 |
| 2014 | 21.5 | 36 |
| 2013 | 28.5 | 28 |
| 2012 | 21.5 | 33 |
| 2011 | 27 | 35 |
| 2010 | 29 | 34 |
| 2009 | 40 | 34 |
| 2008 | 76.8 | 30 |
| 2007 | 44.8 | 29 |
| 2006 | 29 | 32 |
| 2005 | 34.2 | 28 |
| 2004 | 29.9 | 29 |
| 2003 | 23.3 | 33 |
| 2002 | 41.2 | 23 |
| 2001 | 41.9 | 28 |
| 2000 | 48.1 | 26 |
| 1999 | 33 | 28 |
| 1998 | 58.6 | 20 |
| 1997 | 75.7 | 10 |
| 1996 | 35.6 | 22 |
| 1995 | 21.6 | 30 |