Year	%
1971	22.48601
1972	25.85079
1973	28.61837
1974	29.44953
1975	26.00319
1976	30.69827
1978	31.50139
1979	30.80066
1993	41.81973
1998	62.93556
1999	60.56778
2000	62.19793
2002	61.92542
2004	67.94847
2005	65.53328
2006	67.58143
2007	74.22284
2008	74.28429
2009	76.08282
2011	72.85261
2012	69.01551
2013	70.64561
2014	77.24833
2015	78.19348
2016	76.97813
2017	80.78387