Year	% of total
1971	74.6607032875427
1972	77.1741106583994
1973	74.36663391922895
1974	75.39746304958726
1975	75.74642476416517
1976	76.1939197382069
1977	75.88187791122108
1978	78.02470363692647
1979	75.01181304752757
1980	80.9287927914084
1981	78.03791049148656
1982	77.83653444249799
1983	78.87594412276876
1984	81.09747747485775
1985	81.43376237594615
1986	77.05831274025262
1987	78.63751137101558
1988	80.38140353344528
1989	79.6938123131685
1990	76.59397508005652
1991	69.82499607195118
1992	56.07929064573297
1993	53.47897795794464
1994	54.84691480319333
1995	49.541641185572324
1996	45.453763744009024
1997	41.449340236683945
1998	45.29481829963517
1999	58.23879385471522
2000	58.71509800553659
2001	60.95582784156346
2002	63.23313038499602
2003	64.52837122236869
2004	65.57827326143054
2005	66.48668055056278
2006	64.45598990218929
2007	65.1223924710814
2008	63.84717579109021
2009	63.42172640051569
2010	63.23900374851345
2011	61.50276527493236
2012	57.754081722154694
2013	56.395338812823184
2014	61.42180139426375