| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 13.83 | 8 |
| 2015 | 9.02 | 19 |
| 2014 | 4.57 | 55 |
| 2013 | 5.85 | 42 |
| 2012 | 6.28 | 49 |
| 2011 | 8.41 | 45 |
| 2010 | 5.7 | 56 |
| 2009 | -.01 | 152 |
| 2008 | 15.52 | 30 |
| 2007 | 8.53 | 40 |
| 2006 | 13.07 | 12 |
| 2005 | 15.73 | 12 |
| 2004 | 22.81 | 5 |
| 2003 | 39.28 | 3 |
| 2002 | 9.85 | 35 |
| 2001 | 14.17 | 18 |
| 2000 | 13.71 | 22 |
| 1999 | 8.67 | 36 |
| 1998 | 10.63 | 41 |
| 1997 | 20.56 | 23 |
| 1996 | 20.58 | 38 |
| 1995 | 27.61 | 37 |
| 1994 | 39.33 | 29 |
| 1993 | 29.71 | 33 |
| 1992 | 19.36 | 37 |
| 1991 | 15.42 | 49 |
| 1990 | 21.28 | 33 |
| 1989 | 6.92 | 69 |
| 1988 | 4.11 | 89 |
| 1987 | -11.45 | 128 |
| 1986 | 3.28 | 83 |