Year	% of total
1990	58.725345796012355
1991	57.428411571166656
1992	54.392242723030414
1993	52.565664552141904
1994	49.2842066445061
1995	45.520549317325475
1996	40.61150934433607
1997	41.044793352063735
1998	37.796327648028345
1999	40.13161388277602
2000	40.790065572089794
2001	40.562972425995326
2002	39.10165404104048
2003	38.33310418819476
2004	37.91345074965099
2005	36.266241311861634
2006	35.465653967504835
2007	30.142450662152896
2008	31.582314554561634
2009	25.809019156538746
2010	24.438150685230337
2011	19.97818613774501
2012	21.494084511328058
2013	17.58677996066535
2014	19.91964325911998
2015	17.423944623094748
2016	18.325028978951785