Year	% of total
1960	77.89855072463769
1961	79.74276527331192
1962	79.46428571428571
1963	79.22535211267605
1964	76.18181818181819
1965	74.70489038785834
1966	74.42528735632185
1967	71.54582763337892
1968	71.12171837708831
1969	68.47457627118645
1970	66.307541625857
1971	67.56529064869419
1972	72.3846653671215
1973	66.11226611226611
1974	55.780590717299575
1975	53.47166799680766
1976	53.629629629629626
1977	51.53846153846153
1978	50.59288537549408
1979	49.78250362493959
1980	30.425531914893618
1981	47.65234765234766
1982	43.05067737079779
1983	41.03796251802018
1984	37.67572633552015
1985	34.993020009306655
1986	35.639508420573506
1987	37.93103448275862
1988	35.18518518518518
1989	45.632653061224495
1990	35.942661157024794
1991	54.24661800486618
1992	63.19026785714286
1993	71.56850241545895
1994	75.05355140186916
1995	91.0168205128205
1996	89.16208121827411
1997	95.39155405405407
1998	90.45266666666666
1999	93.95915824915825
2000	89.766309148265
2001	97.14133540372671
2002	97.10216
2003	94.75313868613138
2004	87.70027972027972
2005	96.22496314496316
2006	87.55528395061728
2007	80.1178672985782
2008	91.10340527577938
2009	79.11212962962962
2010	76.30242358078603
2011	74.9406746031746
2012	68.93639737991266
2013	69.5887891440501
2014	73.97224137931035
2015	65.89027613412229
2016	68.20768762677486