Year	% of total
1970	91.52771821617685
1971	91.5902496060478
1972	91.85049150795109
1973	91.2626063456617
1974	91.0706613839636
1975	91.06257821868526
1976	91.18075822638087
1977	91.09347546227667
1978	91.52251028136325
1979	91.290253551084
1980	90.87629192757025
1981	91.2779392632488
1982	91.01395510396563
1983	91.16171684148824
1984	90.61075459667387
1985	90.7202164438769
1986	90.76501297104636
1987	90.80008054649802
1988	91.0784704789511
1989	91.04604311195521
1990	97.82244556113902
1991	98.27586206896551
1992	98.45238095238096
1993	97.04209328782709
1994	97.25877192982456
1995	97.2457627118644
1996	97.49768303985171
1997	97.51609935602575
1998	97.47292418772562
1999	97.55686604886267
2000	97.78117827084928
2001	97.289972899729
2002	97.4188176519567
2003	97.5705329153605
2004	97.5885455915599
2005	97.72888573456352
2006	97.70514603616134
2007	97.82894736842105
2008	97.81631342324984