| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 18.16 | 17 |
| 2015 | 16.66 | 32 |
| 2014 | 10.7 | 66 |
| 2013 | 4.31 | 131 |
| 2012 | 6.99 | 105 |
| 2011 | 16.46 | 48 |
| 2010 | 9.23 | 104 |
| 2009 | 10.38 | 82 |
| 2008 | 12.15 | 100 |
| 2007 | 21.13 | 64 |
| 2006 | 30.76 | 34 |
| 2005 | 2.25 | 156 |
| 2004 | 25.22 | 32 |
| 2003 | 8.81 | 105 |
| 2002 | 7.96 | 107 |
| 2001 | 23.83 | 53 |
| 2000 | 17.15 | 61 |
| 1999 | 19.18 | 49 |
| 1998 | 6.19 | 107 |
| 1997 | 20.82 | 56 |
| 1996 | 15.95 | 74 |
| 1995 | 16.22 | 74 |
| 1994 | 52.55 | 22 |
| 1993 | 24.22 | 51 |
| 1992 | 22.26 | 49 |
| 1991 | 31.11 | 32 |
| 1990 | 4.48 | 100 |
| 1989 | 33.69 | 27 |
| 1988 | 22.44 | 42 |
| 1987 | 18.45 | 55 |
| 1986 | 25.62 | 29 |