| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 53.2 | 70 |
| 2015 | 55.61 | 75 |
| 2014 | 50.62 | 81 |
| 2013 | 48.47 | 84 |
| 2012 | 46.09 | 81 |
| 2011 | 42.66 | 91 |
| 2010 | 40.72 | 96 |
| 2009 | 41.05 | 97 |
| 2008 | 33.25 | 110 |
| 2007 | 28.73 | 122 |
| 2006 | 25.59 | 125 |
| 2005 | 25.7 | 121 |
| 2004 | 26.01 | 119 |
| 2003 | 25.63 | 118 |
| 2002 | 27.05 | 113 |
| 2001 | 30.63 | 101 |
| 2000 | 24.17 | 107 |
| 1999 | 25.65 | 103 |
| 1998 | 24.18 | 104 |
| 1997 | 25.48 | 98 |
| 1996 | 26.1 | 95 |
| 1995 | 26.9 | 93 |
| 1994 | 31.75 | 81 |
| 1993 | 30.3 | 87 |
| 1992 | 27.89 | 91 |
| 1991 | 23.6 | 96 |
| 1990 | 20.83 | 102 |
| 1989 | 19.51 | 102 |
| 1988 | 17.4 | 109 |
| 1987 | 18.6 | 103 |
| 1986 | 19.53 | 103 |