Year	%
1971	10.84038
1972	9.59112
1973	9.52452
1974	8.764
1976	9.10033
1977	8.31542
1985	85.50021
1986	88.19866
1987	87.7594
1988	86.56504
1989	83.27683
1990	82.74675
1991	85.24013
2011	79.30249
2012	74.93462
2013	71.82618
2014	68.46453
2015	72.02583
2016	82.41147
2017	72.66696