Year	% of total
1970	53.60386555021191
1971	52.85450697769085
1972	53.018200960525554
1973	53.36526582915349
1974	48.799284499929115
1975	49.353492959817785
1976	49.15309418342713
1977	52.709216031270145
1978	49.358359013526176
1979	49.62924813244427
1980	52.61151875341166
1981	49.52688347644
1982	49.730152618267155
1983	46.78533079000074
1984	46.833512367422344
1985	44.69609416621975
1986	44.51029058030449
1987	45.109225014066
1988	42.43671287681719
1989	44.397908472167984
1990	60.068259385665534
1991	58.879999999999995
1992	56.4945226917058
1993	53.94932935916542
1994	52.06847360912982
1995	50.2724795640327
1996	50.90909090909091
1997	47.961630695443645
1998	50.27624309392266
1999	45.79008073817762
2000	47.406639004149376
2001	41.340206185567006
2002	39.75903614457831
2003	40.359168241965975
2004	36.892278360343184
2005	41.161178509532064
2006	39.02439024390244
2007	36.915077989601386
2008	36.470588235294116