Year Total 1971 4848 1972 5035 1973 5343 1974 5475 1975 5455 1976 5783 1977 6023 1978 6175 1979 6403 1980 6745 1981 6878 1982 7330 1983 7780 1984 7973 1985 8417 1986 8950 1987 8780 1988 9824 1989 10230 1990 10760 1991 10850 1992 11370 1993 11960 1994 12450 1995 12780 1996 12960 1997 13100 1998 13700 1999 14440 2000 15160 2001 16180 2002 16740 2003 17550 2004 18430 2005 19340 2006 21230 2007 22130 2008 23390 2009 24840