| 时间 | 值 （人/平方公里） | 世界排名 |
|---|---|---|
| 2016 | 31.5 | 167 |
| 2015 | 31.8 | 166 |
| 2014 | 32.1 | 163 |
| 2013 | 32.4 | 162 |
| 2012 | 32.7 | 161 |
| 2011 | 33.1 | 162 |
| 2010 | 33.7 | 160 |
| 2009 | 34.4 | 158 |
| 2008 | 35 | 155 |
| 2007 | 35.4 | 153 |
| 2006 | 35.7 | 152 |
| 2005 | 36 | 152 |
| 2004 | 36.4 | 151 |
| 2003 | 36.8 | 150 |
| 2002 | 37.1 | 148 |
| 2001 | 37.6 | 145 |
| 2000 | 38.1 | 144 |
| 1999 | 38.4 | 141 |
| 1998 | 38.7 | 141 |
| 1997 | 39.1 | 137 |
| 1996 | 39.5 | 135 |
| 1995 | 40 | 135 |
| 1994 | 40.5 | 132 |
| 1993 | 41.2 | 131 |
| 1992 | 42 | 128 |
| 1991 | 42.6 | 125 |
| 1990 | 42.8 | 123 |
| 1989 | 42.9 | 119 |
| 1988 | 42.7 | 117 |
| 1987 | 42.2 | 117 |
| 1986 | 41.8 | 117 |