| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 39.51 | 4 |
| 2015 | 18.6 | 27 |
| 2014 | 15.77 | 28 |
| 2013 | 18.89 | 28 |
| 2012 | 12.35 | 65 |
| 2011 | 6.66 | 111 |
| 2010 | 12.42 | 80 |
| 2009 | 9.47 | 87 |
| 2008 | 10.48 | 108 |
| 2007 | 19.11 | 73 |
| 2006 | 15 | 103 |
| 2005 | 11.49 | 100 |
| 2004 | 16.24 | 67 |
| 2003 | 21.28 | 41 |
| 2002 | 12.63 | 81 |
| 2001 | 13.22 | 86 |
| 2000 | 11.58 | 92 |
| 1999 | 5.66 | 132 |
| 1998 | 10.78 | 84 |
| 1997 | 10.77 | 99 |
| 1996 | 10.84 | 95 |
| 1995 | 9.9 | 98 |
| 1994 | 11.21 | 102 |
| 1993 | 13.25 | 80 |
| 1992 | 19.43 | 60 |
| 1991 | 19.34 | 54 |
| 1990 | 28.73 | 32 |
| 1989 | 17.5 | 58 |
| 1988 | 21.55 | 48 |
| 1987 | 20.96 | 45 |
| 1986 | 20.95 | 38 |