Year	% of total
1971	41.904761904761905
1972	39.83885407341092
1973	34.63375796178344
1974	35.842293906810035
1975	38.57493857493858
1976	32.509403546480385
1977	25.39827036868457
1978	30.36468330134357
1979	23.18508829300196
1980	25.86002372479241
1981	21.1340206185567
1982	21.62358057501812
1983	39.995352079944226
1984	71.27425044091711
1985	71.93944712593243
1986	80.04788507581804
1987	84.88112927191679
1988	85.55220705548662
1989	85.8727682440631
1990	78.54780280359111
1991	72.77028964726125
1992	69.12173429683158
1993	78.39697746592903
1994	80.6114931237721
1995	61.22909004626883
1996	67.92291220556746
1997	63.05732484076433
1998	59.74288337924701
1999	69.6255335661622
2000	71.70184696569922
2001	63.99095022624435
2002	63.299125168236884
2003	62.1946994630175
2004	57.57340375951531
2005	54.303747534516766
2006	50.65719360568384
2007	55.19789885169802
2008	60.02019450496891
2009	49.66341752383004
2010	44.26674868009637
2011	54.19100467289719
2012	53.56501947739309
2013	47.45711706289498
2014	47.13868432961698
2015	50.70073557878436