| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2015 | 5.59 | 37 |
| 2014 | 6.13 | 34 |
| 2013 | 7.87 | 23 |
| 2012 | 16 | 10 |
| 2011 | 12.69 | 21 |
| 2010 | 6.2 | 50 |
| 2009 | 12.14 | 12 |
| 2008 | 10.28 | 74 |
| 2007 | 7.03 | 63 |
| 2006 | 7.25 | 56 |
| 2005 | 5.03 | 78 |
| 2004 | 4.74 | 65 |
| 2003 | 5.3 | 64 |
| 2002 | 5.32 | 57 |
| 2001 | 5.15 | 68 |
| 2000 | 5.92 | 56 |
| 1999 | 7.89 | 41 |
| 1998 | 12.8 | 33 |
| 1997 | 16.09 | 31 |
| 1996 | 20.98 | 36 |
| 1995 | 27.43 | 38 |
| 1994 | 34.08 | 39 |
| 1993 | 25.28 | 35 |
| 1992 | 21.85 | 35 |
| 1991 | 28.7 | 30 |
| 1990 | 35.83 | 19 |
| 1989 | 25.85 | 23 |
| 1988 | 31.19 | 22 |
| 1987 | 29.95 | 15 |
| 1986 | 32.43 | 17 |