| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 52.6 | 181 |
| 2015 | 52.7 | 178 |
| 2014 | 52.9 | 177 |
| 2013 | 53 | 176 |
| 2012 | 53.1 | 176 |
| 2011 | 53.1 | 175 |
| 2010 | 53.3 | 175 |
| 2009 | 53 | 176 |
| 2008 | 52.7 | 176 |
| 2007 | 52.3 | 177 |
| 2006 | 51.9 | 177 |
| 2005 | 51.4 | 179 |
| 2004 | 50.7 | 183 |
| 2003 | 50 | 188 |
| 2002 | 49.2 | 190 |
| 2001 | 48.4 | 191 |
| 2000 | 47.7 | 193 |
| 1999 | 47.5 | 194 |
| 1998 | 47.4 | 194 |
| 1997 | 47.4 | 193 |
| 1996 | 47.4 | 193 |
| 1995 | 47.6 | 193 |
| 1994 | 47.7 | 193 |
| 1993 | 47.9 | 193 |
| 1992 | 48.2 | 192 |
| 1991 | 48.8 | 191 |
| 1990 | 49.5 | 184 |
| 1989 | 49.6 | 181 |
| 1988 | 49.9 | 179 |
| 1987 | 50.3 | 170 |
| 1986 | 50.7 | 163 |