| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2015 | 0.48 | 120 |
| 2014 | 3.54 | 69 |
| 2013 | 4.13 | 72 |
| 2012 | 4.94 | 72 |
| 2011 | 5.64 | 75 |
| 2010 | 6.28 | 48 |
| 2009 | 2.22 | 105 |
| 2008 | 7.35 | 110 |
| 2007 | 7.25 | 60 |
| 2006 | 6.24 | 71 |
| 2005 | 12.13 | 24 |
| 2004 | 10.37 | 32 |
| 2003 | 5.15 | 67 |
| 2002 | 3.9 | 71 |
| 2001 | 4.71 | 72 |
| 2000 | 3.25 | 89 |
| 1999 | 4.07 | 72 |
| 1998 | 8.03 | 55 |
| 1997 | 4.63 | 90 |
| 1996 | 4.68 | 103 |
| 1995 | 6.54 | 102 |
| 1994 | 4.13 | 111 |
| 1993 | 9.37 | 73 |
| 1992 | 10.14 | 58 |
| 1991 | 5.63 | 94 |
| 1990 | 6.6 | 83 |
| 1989 | 12.93 | 43 |
| 1988 | 1.32 | 113 |
| 1987 | 8.15 | 58 |
| 1986 | 7.43 | 60 |