Year	% of total
1971	33.169934640522875
1972	52.198581560283685
1973	54.71976401179941
1974	49.75609756097561
1975	46.3718820861678
1976	43.05283757338552
1977	23.356401384083046
1978	28.558875219683657
1979	48.30230010952902
1980	51.14427860696517
1981	48.05825242718447
1982	42.41516966067864
1983	28.701594533029613
1984	25.160599571734476
1985	25.581395348837212
1986	24.559932942162614
1987	31.37715179968701
1988	30.234375000000004
1989	34.316869788325846
1990	27.659574468085108
1991	22.362309223623093
1992	15.680292861500917
1993	27.838616714697405
1994	21.93585337915235
1995	21.940700808625337
1996	21.625689914701454
1997	19.902200488997554
1998	13.062665489849955
1999	18.144044321329638
2000	8.93236920459379
2001	7.817460317460317
2002	11.564885496183207
2003	10.714285714285714
2004	10.985626283367557
2005	14.19206817436906
2006	9.82769623484365
2007	9.53865336658354
2008	15.888128533174651
2009	8.601216333622936
2010	13.774255261000274
2011	11.610878661087867
2012	10.394443066236665
2013	10.945751320211233
2014	8.884390463337832
2015	6.442454684428915