| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2015 | 17.81 | 81 |
| 2014 | 19.73 | 72 |
| 2013 | 22.32 | 68 |
| 2012 | 28.9 | 50 |
| 2011 | 28.38 | 50 |
| 2010 | 26.2 | 54 |
| 2009 | 21.86 | 71 |
| 2008 | 27.93 | 48 |
| 2007 | 25.59 | 59 |
| 2006 | 26.95 | 53 |
| 2005 | 42.28 | 28 |
| 2004 | 46.89 | 19 |
| 2003 | 44.33 | 19 |
| 2002 | 50.95 | 11 |
| 2001 | 52.34 | 11 |
| 2000 | 50.87 | 10 |
| 1999 | 46.79 | 15 |
| 1998 | 44 | 20 |
| 1997 | 41.79 | 19 |
| 1996 | 41.66 | 21 |
| 1995 | 49.11 | 13 |
| 1994 | 52.06 | 11 |
| 1993 | 59.56 | 6 |
| 1992 | 66.71 | 4 |