Year	%
1971	40.74334
1972	35.23862
1973	42.40216
1974	39.29916
1975	43.15553
1976	54.42742
1977	52.95625
1978	53.89208
1980	60.49542
1985	31.58651
1988	49.71466
1989	42.93619
1990	68.40839
1991	44.65345
1996	47.37138
1998	49.025
1999	47.99867
2000	49.91059
2001	58.71742
2002	58.41112
2003	63.23199
2004	74.48514
2005	72.35167
2006	52.62454
2007	59.59459
2008	58.725
2009	71.90899
2010	72.24763
2011	64.00553
2012	69.67891
2013	64.82125
2015	58.26901