| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 79.23 | 53 |
| 2015 | 78.83 | 56 |
| 2014 | 78.36 | 62 |
| 2013 | 77.89 | 65 |
| 2012 | 77.36 | 68 |
| 2011 | 76.83 | 74 |
| 2010 | 76.34 | 75 |
| 2009 | 76.04 | 75 |
| 2008 | 75.78 | 80 |
| 2007 | 75.57 | 85 |
| 2006 | 75.43 | 84 |
| 2005 | 74.54 | 94 |
| 2004 | 73.7 | 100 |
| 2003 | 72.92 | 109 |
| 2002 | 72.2 | 116 |
| 2001 | 71.57 | 124 |
| 2000 | 71.02 | 130 |
| 1999 | 71.45 | 128 |
| 1998 | 71.96 | 123 |
| 1997 | 72.5 | 120 |
| 1996 | 73 | 118 |
| 1995 | 73.42 | 118 |
| 1994 | 74.32 | 110 |
| 1993 | 75.09 | 103 |
| 1992 | 75.76 | 101 |
| 1991 | 76.38 | 99 |
| 1990 | 77.02 | 96 |