Year	% of total
1971	89.63653785450421
1972	89.17889813971063
1973	89.42289397517743
1974	89.15926040205206
1975	88.77912328085789
1976	89.22440371463739
1977	89.0246469725816
1978	89.06793066183118
1979	88.73553321093775
1980	89.02954741017382
1981	89.8817022811823
1982	90.50629181867768
1983	90.26569560315558
1984	89.34912923787545
1985	88.77537664174481
1986	88.04374172874556
1987	88.55550625541555
1988	87.16735249304026
1989	85.7587484321716
1990	86.15600714648338
1991	86.27079086727936
1992	85.15415756073749
1993	86.65011080026596
1994	86.15283213491134
1995	86.3013700350014
1996	84.99355587955463
1997	84.90715771349622
1998	84.4570529558715
1999	84.65273180562984
2000	84.24342648091917
2001	85.67808449644197
2002	84.89834277443146
2003	86.02328014633287
2004	86.99483552941095
2005	87.1567180454355
2006	87.11379815531447
2007	87.71745546414748
2008	88.14866880549431
2009	87.67566972529116
2010	87.46124140842917
2011	87.03964200759225
2012	87.15523380623391
2013	86.5753045830766
2014	86.79143169140163