| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 76.4 | 79 |
| 2015 | 76.17 | 82 |
| 2014 | 75.87 | 85 |
| 2013 | 75.54 | 86 |
| 2012 | 75.17 | 88 |
| 2011 | 74.8 | 92 |
| 2010 | 74.43 | 94 |
| 2009 | 73.93 | 98 |
| 2008 | 73.44 | 102 |
| 2007 | 72.94 | 107 |
| 2006 | 72.45 | 111 |
| 2005 | 72.1 | 114 |
| 2004 | 71.84 | 117 |
| 2003 | 71.64 | 118 |
| 2002 | 71.65 | 120 |
| 2001 | 71.69 | 123 |
| 2000 | 71.71 | 124 |
| 1999 | 71.73 | 126 |
| 1998 | 71.74 | 127 |
| 1997 | 71.75 | 128 |
| 1996 | 71.7 | 129 |
| 1995 | 71.82 | 129 |
| 1994 | 72.04 | 129 |
| 1993 | 72.44 | 128 |
| 1992 | 72.65 | 129 |
| 1991 | 73.18 | 129 |
| 1990 | 73.21 | 130 |