Year	% of total
1990	23.2618405854427
1995	22.7575382501329
2000	26.3390709599074
2005	28.6333102411763
2010	29.591007274211
2011	29.1091059873562
2012	24.7444815603143
2013	21.4642915292117
2014	7.82498069513683
2015	3.94446924370343
2016	1.34838660266684
2017	1.3407797137591