Year	% of total
1971	12.27481994504212
1972	12.25418027983592
1973	12.584164192434852
1974	12.47227336509126
1975	12.247963752451192
1976	11.166851158475872
1977	11.37491528248395
1978	11.361244019733666
1979	12.644430591057674
1980	10.516088582347455
1981	12.278697809752128
1982	9.737507071087323
1983	12.273035284350966
1984	13.704550372385023
1985	10.671876594988792
1986	9.451565389106053
1987	10.192295095436661
1988	10.523511900088986
1989	8.986425035666317
1990	11.162352795991504
1991	8.779668506790623
1992	7.866010165427206
1993	7.351352329398433
1994	4.710080753453098
1995	5.493197163640392
1996	5.815207923823852
1997	4.766045299077456
1998	4.125985415208054
1999	3.086504485946448
2000	2.036553246937591
2001	1.6397332914050204
2002	1.7145850838298597
2003	2.015286660534891
2004	2.112644231419531
2005	2.5463496121034153
2006	2.6785004939691595
2007	2.8737596410988906
2008	3.0674861809859735
2009	2.7425693621531435
2010	3.0782110050489675
2011	3.6916473208345075
2012	2.871716469675017
2013	4.176638239868235
2014	5.3558141424822026