Year	% of total
1990	76.56910027665289
1991	75.53221857713706
1992	77.33716681068891
1993	76.59765543561403
1994	74.18683486711136
1995	72.41149992499237
1996	69.01980774127288
1997	68.30839290280345
1998	70.27001516050215
1999	72.99136026966241
2000	68.79883999089643
2001	70.85878057747148
2002	70.80227645957031
2003	70.00704272536028
2004	65.91932521258263
2005	66.41002644555635
2006	65.42110889469528
2007	63.870357308924646
2008	64.51332142733175
2009	64.56208551644973
2010	63.172134694067296
2011	61.499476267227436
2012	62.56539658068439
2013	61.82371990333945
2014	61.54152298151492
2015	59.66709993835879
2016	59.22933045105565