Year	% of total
1970	57.54334504786218
1971	58.465597179780914
1972	57.566566684416564
1973	57.55069974248741
1974	57.5468566377351
1975	57.731834076465226
1976	57.96359852131968
1977	58.23298197187775
1978	57.81799177621407
1979	56.91134945491258
1980	57.50539429990334
1981	56.58723659049335
1982	56.78917254544419
1983	54.446815905246105
1984	51.69545493424684
1985	51.20619260103908
1986	50.447812369870526
1987	50.84308848079109
1988	50.94996492113937
1989	51.332180080810396
1990	59.25925925925925
1991	58.80149812734082
1992	58.42696629213483
1993	59.48905109489051
1994	58.14814814814815
1995	56.53846153846154
1996	48.214285714285715
1997	48.23008849557522
1998	46.3963963963964
1999	41.904761904761905
2000	40.29126213592233
2001	47.950819672131146
2002	51.85185185185185
2003	57.37179487179487
2004	60.23391812865497
2005	60.893854748603346
2006	66.66666666666666
2007	61.273209549071616
2008	56.896551724137936