Year	% of total
1990	43.77126043100017
1991	43.27118241729291
1992	40.56360044102034
1993	40.64270380544489
1994	40.08174559933855
1995	39.33906126661025
1996	39.49269467378974
1997	39.39768247558235
1998	39.48425467539299
1999	39.886432548355124
2000	39.725118400837765
2001	39.38032277699716
2002	38.45579692925535
2003	37.812418319828154
2004	37.135907986121886
2005	35.79576382186075
2006	34.85548868343046
2007	33.30367325602441
2008	33.454226007559676
2009	33.444842815266675
2010	32.21991581558241
2011	31.1349441116634
2012	31.298823512152733
2013	30.933270293134797
2014	31.325385263388867
2015	31.454452814043325
2016	31.444026727638455