Year	% of total
1970	51.567365416043195
1971	53.91883050787969
1972	51.037354769335664
1973	50.01497383896777
1974	48.7158521566133
1975	52.990085810706546
1976	51.16090251919656
1977	50.12704619894682
1978	45.741690660642995
1979	46.81760386996662
1980	55.25785929058596
1981	56.9849279512171
1982	56.75267072847028
1983	53.238866589759084
1984	56.8133089426018
1985	57.850723970928456
1986	57.035247048752204
1987	58.12837008506677
1988	61.31099208443271
1989	58.146188125055176
1990	69.53316953316954
1991	69.0176322418136
1992	67.95865633074936
1993	68.86543535620054
1994	69.86666666666666
1995	66.24040920716112
1996	65.92592592592592
1997	64.66165413533834
1998	64.23357664233576
1999	63.04347826086957
2000	61.59420289855072
2001	59.84455958549223
2002	65.13317191283294
2003	62.532981530343015
2004	61.77215189873417
2005	60.574412532637076
2006	59.56284153005464
2007	60.629921259842526
2008	61.02150537634409