Year	% of total
1971	73.36699861654891
1972	73.52762076634187
1973	73.87058359152198
1974	74.97758100183577
1975	76.86505776407834
1976	76.94818106876123
1977	77.50238987270541
1978	78.92109959019335
1979	80.13056614892655
1980	66.1389234676909
1981	64.84839391666097
1982	64.4494636719817
1983	60.80168506005624
1984	60.67224237114884
1985	59.600957923203445
1986	56.75695870532903
1987	66.16209030450382
1988	64.00658555981161
1989	67.60317378263098
1990	67.20305861776127
1991	66.51871394465242
1992	69.20822225473161
1993	68.57968935298608
1994	71.49556907177217
1995	74.22273213638687
1996	76.49405638888472
1997	78.34940725001567
1998	78.77728042085181
1999	78.13399150134924
2000	82.55108851700491
2001	77.19835063928842
2002	80.86023883720839
2003	81.99133613047185
2004	81.62470716959692
2005	83.2741378211675
2006	85.95852752103565
2007	82.04786586321333
2008	82.60450094561111
2009	80.95941747973208
2010	82.32042867872296
2011	82.99562132545896
2012	83.52557303407848
2013	84.18089927540791
2014	84.15328998687747