Year	% of total
1990	67.62936221419976
1991	58.02622253720765
1992	65.75378195096505
1993	73.29255861365954
1994	74.43693693693693
1995	73.81251570746419
1996	59.50095969289827
1997	65.53484243231247
1998	74.45230291530102
1999	67.08029197080292
2000	68.15764023210832
2001	66.19158878504673
2002	61.9874213836478
2003	57.00628930817611
2004	66.30411601620814
2005	67.79453730126376
2006	55.162543447147826
2007	57.283588346258654
2008	58.94956389836936
2009	62.0757766205782
2010	53.1160404406217
2011	47.374466688546114
2012	60.110264310037294
2013	46.89966178128523
2014	38.786228360241196
2015	33.61648292065787