| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 38 | 11 |
| 2015 | 37.96 | 12 |
| 2014 | 38.48 | 12 |
| 2013 | 39.13 | 12 |
| 2012 | 40.01 | 17 |
| 2011 | 41.21 | 20 |
| 2010 | 42.74 | 29 |
| 2009 | 44.59 | 36 |
| 2008 | 46.85 | 48 |
| 2007 | 49.52 | 66 |
| 2006 | 52.56 | 85 |
| 2005 | 55.87 | 96 |
| 2004 | 59.73 | 103 |
| 2003 | 64.09 | 113 |
| 2002 | 68.95 | 119 |
| 2001 | 74.25 | 124 |
| 2000 | 79.93 | 135 |
| 1999 | 83.92 | 143 |
| 1998 | 87.9 | 151 |
| 1997 | 91.69 | 160 |
| 1996 | 95.12 | 170 |
| 1995 | 98.07 | 178 |
| 1994 | 99.97 | 179 |
| 1993 | 101.06 | 180 |
| 1992 | 101.46 | 181 |
| 1991 | 101.46 | 181 |
| 1990 | 101.26 | 179 |
| 1989 | 100.74 | 179 |
| 1988 | 100.08 | 177 |
| 1987 | 99.23 | 175 |
| 1986 | 97.89 | 165 |