Year	% of total
1990	16.0998641967062
1995	14.4902327070347
2000	15.3795224094136
2005	9.76652919456457
2010	3.96958881429397
2011	10.8950541675568
2012	15.5844156499954
2013	17.0255530245378
2014	13.4095935280462
2015	16.6095895558219
2016	19.6755547444813
2017	19.6855066080211