Year	% of total
1970	62.34364415253145
1971	62.54538262403149
1972	62.017704246655036
1973	62.09936691191314
1974	61.311926528745374
1975	62.19061000615655
1976	62.99634227197275
1977	64.18558934010355
1978	64.43808144304285
1979	64.57870583405322
1980	65.71982219372335
1981	65.64164095618933
1982	64.7223088873413
1983	64.2185902916678
1984	64.34544148787094
1985	65.62098341129322
1986	65.93874335672196
1987	66.18497692819811
1988	66.87432763531605
1989	66.98234890793476
1990	87.82287822878229
1991	87.36059479553904
1992	87.4074074074074
1993	87.06099815157117
1994	7.762706324562838
1995	7.762706324562838
1996	7.973259416272624
1997	8.242562185010566
1998	9.055752497582985
1999	8.997097710415995
2000	10.011158935118763
2001	9.401572276592331
2002	9.28215834270114
2003	10.23034154090548
2004	9.130364893104002
2005	10.207969518971264
2006	9.393502960473676
2007	9.197244031405223
2008	8.895311496467565