| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 6.08 | 89 |
| 2015 | 10.32 | 65 |
| 2014 | 7.28 | 102 |
| 2013 | 5.92 | 118 |
| 2012 | 5.17 | 116 |
| 2011 | 8.34 | 99 |
| 2010 | 6.93 | 117 |
| 2009 | 1.76 | 138 |
| 2008 | 14.74 | 83 |
| 2007 | 23.93 | 55 |
| 2006 | 22.62 | 59 |
| 2005 | 20.7 | 51 |
| 2004 | 13.15 | 87 |
| 2003 | 13.35 | 79 |
| 2002 | 18.29 | 53 |
| 2001 | 20.19 | 61 |
| 2000 | 7.22 | 118 |
| 1999 | 10.91 | 100 |
| 1998 | 13.65 | 61 |
| 1997 | 17.81 | 72 |
| 1996 | 14.28 | 84 |
| 1995 | 16.03 | 75 |
| 1994 | 18.32 | 78 |
| 1993 | 6.31 | 100 |
| 1992 | 2.86 | 115 |
| 1991 | 17.11 | 65 |
| 1990 | 11.85 | 71 |
| 1989 | 20.57 | 49 |
| 1988 | 27.02 | 34 |
| 1987 | 19.52 | 47 |
| 1986 | 8.79 | 88 |