Year	% of total
1971	100
1972	96.26865671641791
1973	96.96969696969697
1974	48.18652849740933
1975	43.47826086956522
1976	50.609756097560975
1977	32.05417607223476
1978	32.11009174311927
1979	40.38461538461539
1980	50.943396226415096
1981	30.756302521008404
1982	26.986506746626688
1983	24.96570644718793
1984	23.270440251572328
1985	22.531939605110338
1986	21.95945945945946
1987	22.011173184357542
1988	22.087912087912088
1989	22.945205479452056
1990	27.607361963190186
1991	27.411167512690355
1992	27.492447129909365
1993	28.128128128128125
1994	29.174484052532833
1995	29.762949956101842
1996	35.99670510708402
1997	35.03184713375796
1998	39.01712583767684
1999	36.89759036144578
2000	38.40304182509506
2001	37.10021321961621
2002	37.24696356275304
2003	40.8735332464146
2004	41.493506493506494
2005	47.903430749682336
2006	42.76276276276276
2007	53.34486735870819
2008	50.49396267837542
2009	47.980349344978166
2010	52.661498708010335
2011	58.402743753062225
2012	57.48613678373382
2013	55.00954198473282
2014	59.65965965965966
2015	56.25587958607714