| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 50.59 | 70 |
| 2015 | 50.69 | 74 |
| 2014 | 50.9 | 80 |
| 2013 | 51.34 | 85 |
| 2012 | 51.98 | 93 |
| 2011 | 52.65 | 96 |
| 2010 | 53.27 | 100 |
| 2009 | 54.36 | 102 |
| 2008 | 55.45 | 105 |
| 2007 | 56.68 | 106 |
| 2006 | 58.31 | 107 |
| 2005 | 60.5 | 112 |
| 2004 | 62.96 | 115 |
| 2003 | 65.91 | 119 |
| 2002 | 69.13 | 120 |
| 2001 | 72.21 | 120 |
| 2000 | 74.82 | 123 |
| 1999 | 77.42 | 124 |
| 1998 | 79.58 | 126 |
| 1997 | 81.4 | 128 |
| 1996 | 83.2 | 131 |
| 1995 | 85.31 | 136 |
| 1994 | 87.23 | 134 |
| 1993 | 88.46 | 134 |
| 1992 | 88.88 | 133 |
| 1991 | 88.65 | 131 |
| 1990 | 88.01 | 128 |
| 1989 | 85.2 | 124 |
| 1988 | 83.3 | 117 |
| 1987 | 81.99 | 113 |
| 1986 | 80.81 | 107 |