| Year | Distance |
|---|---|
| 1980 | 3,746 |
| 1981 | 6,467 |
| 1982 | 7,067 |
| 1983 | 8,561 |
| 1984 | 7,621 |
| 1985 | 8,573 |
| 1986 | 8,537 |
| 1987 | 8,840 |
| 1988 | 7,325 |
| 1989 | 5,590 |
| 1990 | 5,878 |
| 1991 | 5,578 |
| 1992 | 4,977 |
| 1993 | 4,932 |
| 1994 | 5,276 |
| 1995 | 4,750 |
| 1996 | 5,931 |
| 1997 | 5,068 |
| 1998 | 6,448 |
| 1999 | 5,137 |
| 2000 | 2,984 |
| 2001 | 2,898 |
| 2002 | 4,143 |
| 2003 | 4,200 |
| 2004 | 5,089 |
| 2005 | 5,145 |
| 2006 | 5,150 |
| 2007 | 4,728 |
| 2008 | 4,804 |
| 2009 | 4,083 |
| 2010 | 4,026 |
| 2011 | 3,314 |
| 2012 | 4,201 |
| 2013 | 4,236 |
| 2014 | 5,598 |
| 2015 | 6,720 |
| 2016 | 7,676 |
| 2017 | 6,600 |
| 2018 | 6,688 |
| Total | 218,585 |