Year	% of total
1990	52.01531248618234
1991	53.49759746780101
1992	53.50821987442121
1993	53.047089906648125
1994	51.11093285159628
1995	48.858331340145256
1996	48.069014058939786
1997	47.00936397388724
1998	47.5737042216799
1999	48.5600677627195
2000	49.887074565999676
2001	48.9983416860548
2002	46.983318470176
2003	46.80247867072941
2004	45.72174070638447
2005	43.79852479201278
2006	43.216885880561634
2007	40.96163452698003
2008	41.973029421227544
2009	42.70609108138897
2010	40.6186950865625
2011	39.07705531081487
2012	39.513220108242976
2013	39.184620154794004
2014	39.03335783342789
2015	39.54305536423653
2016	38.11672564907093