Year	% of total
1970	55.806357704503895
1971	64.432275257017
1972	59.04366462576649
1973	51.129591866350175
1974	60.15001400732171
1975	59.223394548206734
1976	56.68557277911881
1977	49.16004029154552
1978	41.1006604276057
1979	45.47669979941324
1980	42.88926580162378
1981	45.32722863523354
1982	42.942790355369276
1983	32.54490876639626
1984	34.41994510706877
1985	36.66768938331497
1986	32.267136653873926
1987	30.228441180880527
1988	30.947962931548727
1989	31.36235454271213
1990	17.68807339449541
1991	16.582914572864322
1992	16.207737887765774
1993	16.171505739365294
1994	16.40574037834312
1995	15.608043408873284
1996	15.197757707879164
1997	14.987864077669903
1998	14.404514404514405
1999	13.799126637554584
2000	13.611821540210286
2001	13.208600949455459
2002	12.837285363859364
2003	12.603031108747672
2004	12.564766839378239
2005	12.217997465145753
2006	11.673734098278873
2007	11.96977084349098
2008	11.699566682715455