Year	% of total
1970	27.86863268164994
1971	27.365261148617986
1972	27.400635180646226
1973	27.456469320169774
1974	27.205474431372682
1975	27.41507003267991
1976	27.171125705196875
1977	27.332054808634847
1978	27.338411401302892
1979	27.580154230655108
1980	27.346537495637723
1981	27.091434562266258
1982	27.237601183470527
1983	27.176128017501483
1984	26.51257309124069
1985	26.75562636819405
1986	26.559546311724308
1987	27.220458819468124
1988	26.372647605750387
1989	26.6968145820042
1990	49.67897271268058
1991	48.439352034768866
1992	47.64478764478765
1993	46.58054711246201
1994	45.593726661687825
1995	45.10606624488277
1996	39.35907970419063
1997	38.849813818783616
1998	39.78013029315961
1999	37.536904259805986
2000	36.565910999160366
2001	38.127762153475295
2002	43.00217548948513
2003	44.59366391184573
2004	45.77114427860697
2005	44.97845541929068
2006	44.46959896507115
2007	40.54959785522788
2008	41.157556270096464