Year	% of total
1992	33.073740182707006
1993	37.40299150180418
1994	36.27568771920056
1995	34.9830416184237
1996	36.064484598898524
1997	40.69450551900437
1998	44.54261215749912
1999	38.42156542839764
2000	39.67503420995289
2001	45.85553206513924
2002	43.178734869003115
2003	41.82858263012466
2004	34.864035858522605
2005	34.54653885235327
2006	38.54973927052683
2007	35.50350681583597
2008	34.02934038107804
2009	32.5372897140448
2010	31.270366667676765
2011	27.284752413958476
2012	23.47303078428218
2013	25.43097886863131
2014	20.422951734537108
2015	19.58514395812538
2016	19.80475662828295