Year	% of total
1970	60.03426002370933
1971	60.87420567465119
1972	59.13646133472225
1973	59.03269781659682
1974	59.61594500192825
1975	58.805925961390294
1976	57.19263479594788
1977	55.61661020865126
1978	55.53798938091653
1979	55.36744263302909
1980	55.755985134822396
1981	55.72974286425659
1982	55.71412210508625
1983	55.071319762190086
1984	55.05880399719203
1985	52.102847121527184
1986	50.656330910868434
1987	50.098231520860814
1988	45.853361196634005
1989	43.37589146895217
1990	56.934306569343065
1991	56.89223057644111
1992	55.91397849462365
1993	54.07608695652174
1994	53.672316384180796
1995	51.59420289855072
1996	49.411764705882355
1997	49.25816023738873
1998	48.50299401197605
1999	49.112426035502956
2000	48.18181818181818
2001	47.633136094674555
2002	47.05882352941176
2003	45.86894586894587
2004	46.849315068493155
2005	46.408839779005525
2006	45.98930481283423
2007	44.17989417989418
2008	41.6