| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 78.71 | 58 |
| 2015 | 78.41 | 62 |
| 2014 | 78.11 | 64 |
| 2013 | 78.07 | 63 |
| 2012 | 78.75 | 58 |
| 2011 | 77.31 | 68 |
| 2010 | 75.43 | 84 |
| 2009 | 75 | 87 |
| 2008 | 74.47 | 94 |
| 2007 | 73.97 | 98 |
| 2006 | 73.56 | 100 |
| 2005 | 73.27 | 103 |
| 2004 | 73.18 | 104 |
| 2003 | 74.8 | 87 |
| 2002 | 73.81 | 101 |
| 2001 | 75.65 | 92 |
| 2000 | 73.99 | 102 |
| 1999 | 75.18 | 93 |
| 1998 | 75.32 | 95 |
| 1997 | 75.42 | 96 |
| 1996 | 75.45 | 100 |
| 1995 | 75.36 | 100 |
| 1994 | 75.3 | 100 |
| 1993 | 75.55 | 100 |
| 1992 | 75.81 | 99 |
| 1991 | 74.92 | 111 |
| 1990 | 74.26 | 124 |