Year	%
1971	22.4144
1972	25.17993
1973	28.73452
1974	28.02999
1975	26.27079
1976	30.00909
1978	30.5562
1979	31.66153
1980	33.76022
1981	36.32865
1982	35.46239
1983	39.37804
1987	55.60152
1988	58.66363
1989	59.55944
1990	56.42631
1991	53.32948
1992	41.73519
1993	42.23095
1998	64.84174
1999	60.5365
2000	61.95547
2002	61.23402
2004	66.83147
2005	65.40999
2006	66.92342
2007	73.62768
2008	73.18979
2009	74.85896
2011	72.07983
2012	68.19726
2013	68.74054
2014	76.55103
2015	77.55105
2016	76.05944
2017	80.10901