| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 0.11 | 122 |
| 2015 | 12.26 | 52 |
| 2014 | 14.72 | 37 |
| 2013 | 18.37 | 30 |
| 2012 | 4.93 | 118 |
| 2011 | 20.01 | 31 |
| 2010 | 14.64 | 65 |
| 2009 | 14.41 | 64 |
| 2008 | 21.85 | 42 |
| 2007 | 24.1 | 54 |
| 2006 | 18.87 | 78 |
| 2005 | 10.61 | 111 |
| 2004 | 31.37 | 23 |
| 2003 | 17.18 | 58 |
| 2002 | 21.58 | 41 |
| 2001 | 7.77 | 116 |
| 2000 | 4.17 | 131 |
| 1999 | 3.53 | 140 |
| 1998 | 23 | 24 |
| 1997 | 23.32 | 53 |
| 1996 | 26.13 | 41 |
| 1995 | 15.41 | 79 |
| 1994 | 23.99 | 65 |
| 1993 | 35.9 | 29 |
| 1992 | 12.56 | 81 |
| 1991 | 24.76 | 42 |
| 1990 | 18.59 | 56 |
| 1989 | 19.91 | 51 |
| 1988 | 14.26 | 74 |
| 1987 | 11.9 | 73 |
| 1986 | 25.36 | 32 |