| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 78.61 | 61 |
| 2015 | 78.75 | 58 |
| 2014 | 78.94 | 55 |
| 2013 | 78.77 | 58 |
| 2012 | 78.55 | 59 |
| 2011 | 78.94 | 60 |
| 2010 | 77.68 | 65 |
| 2009 | 77.34 | 68 |
| 2008 | 76.95 | 71 |
| 2007 | 76.56 | 75 |
| 2006 | 76.21 | 78 |
| 2005 | 75.91 | 82 |
| 2004 | 75.61 | 83 |
| 2003 | 75.36 | 85 |
| 2002 | 75.27 | 87 |
| 2001 | 75.1 | 94 |
| 2000 | 74.92 | 93 |
| 1999 | 74.65 | 97 |
| 1998 | 74.35 | 103 |
| 1997 | 74.06 | 110 |
| 1996 | 73.82 | 113 |
| 1995 | 73.7 | 115 |
| 1994 | 73.39 | 119 |
| 1993 | 73.29 | 120 |
| 1992 | 73.18 | 124 |
| 1991 | 73.11 | 130 |
| 1990 | 73.28 | 129 |