Year	% of total
1990	43.736580724340016
1991	43.029732205658945
1992	31.773622121589796
1993	31.65620665544344
1994	31.372073822518153
1995	28.00473057228363
1996	27.974562417000175
1997	27.518034024552247
1998	31.24086431242915
1999	32.207305595178816
2000	28.65162330782363
2001	31.874953468512985
2002	29.587055828890534
2003	28.306890045364558
2004	29.245858487532207
2005	30.284703675707352
2006	31.411386722341817
2007	28.59866480916881
2008	28.07201921260456
2009	23.28809432035415
2010	20.57485777155908
2011	18.877978115761092
2012	19.559749384490946
2013	17.198629745819623
2014	14.490291113381845
2015	13.05621533573435