Year	% of total
1960	82.95454545454544
1961	83.60655737704919
1962	84.72400513478819
1963	84.50363196125907
1964	85.6341189674523
1965	84.64088397790054
1966	84.64646464646465
1967	85.72895277207392
1968	87.41328047571852
1969	85.08845829823083
1970	82.91550603528319
1971	85.78296703296702
1972	85.0832266325224
1973	87.93456032719837
1974	87.6267748478702
1975	86.77309007981756
1976	85.87672052663076
1977	87.5657894736842
1978	87.67650834403082
1979	82.54913639070877
1980	87.77448071216617
1981	81.00461893764435
1982	86.02279544091182
1983	89.77955911823648
1984	91.15964638585544
1985	93.80974055530268
1986	94.18714555765595
1987	94.33962264150945
1988	94.11201531833413
1989	94.39890710382514
1990	138.197615658363
1991	114.07286931818182
1992	136.91178062678063
1993	95.77508228460795
1994	94.81488908606921
1995	85.05785714285715
1996	80.84540368271954
1997	84.86615623062616
1998	89.00091076923077
1999	85.74277157956548
2000	85.15770899808551
2001	84.23895796329188
2002	83.59627672209025
2003	90.40071223434806
2004	78.87741610738254
2005	77.60543402777778
2006	75.73495995070856
2007	73.02324916943522
2008	78.27256698821007
2009	81.36992700729927
2010	78.50330459770116
2011	80.61167138810198
2012	82.44502981260648
2013	82.49172117039588
2014	82.97065356856456
2015	77.82716081330868
2016	77.16391226177633