Year	% of total
1960	98.2469031231268
1961	98.30405988617062
1962	98.39621714892378
1963	98.42085721457043
1964	98.51842370724432
1965	97.81227335823385
1966	97.80813345516523
1967	97.73769234204674
1968	97.84306045753839
1969	97.69032809473684
1970	97.99588636411977
1971	97.75131941395898
1972	97.64559402099279
1973	97.75988318158447
1974	97.52833947666007
1975	97.5478641117396
1976	97.46301961334476
1977	96.94853305660044
1978	97.247835293646
1979	97.48717968996998
1980	97.11355254471654
1981	96.55742895871141
1982	96.55668897906583
1983	96.2190621767041
1984	95.74603926013383
1985	95.01893745099947
1986	94.51202461249031
1987	94.02746948498982
1988	93.297837390067
1989	93.22472288932785
1990	89.25330505032075
1991	88.74399055760027
1992	88.52183424826393
1993	87.65971908158531
1994	86.96654716934603
1995	86.7928836368446
1996	86.35280843859
1997	85.71687480874043
1998	85.45168272177118
1999	85.16067308618699
2000	84.74255215818515
2001	84.67572611381378
2002	83.91131137246983
2003	83.95075141923327
2004	83.26790699260303
2005	83.18497664383997
2006	83.39174071863322
2007	83.06888312623224
2008	81.70598525004269
2009	79.88391258146733
2010	80.25491985092357
2011	80.09576321015646
2012	78.56672775805606
2013	77.7076786589043
2014	76.24536377075727
2015	79.36373837402914