Year	% of total
1990	3.18802341339859
1995	3.3118108259618
2000	10.9867883655577
2005	10.5421390599848
2010	10.0656073968634
2011	13.2813879373112
2012	9.18414575110673
2013	7.85148427303514
2014	3.66827496069444
2015	2.662779193278
2016	1.59819727530986
2017	1.59388097142582