Year	% of total
1990	82.04582733812948
1991	82.44427586206896
1992	83.11866666666667
1993	83.57902597402597
1994	84.01607594936709
1995	84.04490683229814
1996	84.29628048780489
1997	84.31904191616766
1998	83.84777777777778
1999	84.42627906976745
2000	84.02668571428572
2001	84.32028248587571
2002	84.13727777777777
2003	84.82456043956044
2004	84.12529411764706
2005	84.148
2006	84.799375
2007	84.37841836734694
2008	83.7389552238806
2009	81.54709523809524
2010	81.14935185185185
2011	80.47488687782804
2012	79.13
2013	80.06550218340611
2014	80.4835064935065
2015	76.62878923766816
2016	75.27850220264317