| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 14.86 | 43 |
| 2015 | 15.94 | 47 |
| 2014 | 17.11 | 48 |
| 2013 | 17 | 50 |
| 2012 | 19.17 | 46 |
| 2011 | 18.62 | 45 |
| 2010 | 19.44 | 44 |
| 2009 | 21.08 | 38 |
| 2008 | 27.04 | 24 |
| 2007 | 31.08 | 17 |
| 2006 | 32.77 | 17 |
| 2005 | 31.95 | 21 |
| 2004 | 33.27 | 21 |
| 2003 | 37.06 | 19 |
| 2002 | 37.68 | 19 |
| 2001 | 37.29 | 15 |
| 2000 | 36.75 | 15 |
| 1999 | 37.68 | 17 |
| 1998 | 39.53 | 16 |
| 1997 | 44.61 | 12 |
| 1996 | 49.75 | 7 |
| 1995 | 43.9 | 14 |
| 1994 | 40.88 | 17 |
| 1993 | 41.01 | 22 |
| 1992 | 39.05 | 17 |
| 1991 | 36.98 | 21 |
| 1990 | 33.54 | 23 |
| 1989 | 33.61 | 20 |
| 1988 | 31.83 | 26 |