| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2015 | 32.83 | 39 |
| 2014 | 34.82 | 38 |
| 2013 | 37.18 | 31 |
| 2012 | 38.88 | 27 |
| 2011 | 40.43 | 26 |
| 2010 | 39.08 | 28 |
| 2009 | 36.59 | 32 |
| 2008 | 39.55 | 31 |
| 2007 | 41.11 | 26 |
| 2006 | 40.95 | 28 |
| 2005 | 37.73 | 29 |
| 2004 | 35.89 | 37 |
| 2003 | 32.79 | 47 |
| 2002 | 32.19 | 55 |
| 2001 | 31.75 | 55 |
| 2000 | 31.86 | 56 |
| 1999 | 31.48 | 52 |
| 1998 | 31.51 | 51 |
| 1997 | 32.46 | 45 |
| 1996 | 31.92 | 52 |
| 1995 | 32.31 | 53 |
| 1994 | 32.3 | 52 |
| 1993 | 30.51 | 62 |
| 1992 | 28.9 | 69 |
| 1991 | 28.08 | 75 |