Year	% of total
1990	23.158148124616666
1991	22.910954233251925
1992	23.597858118501247
1993	22.948811578518235
1994	24.799345276463832
1995	24.43308492118672
1996	23.564874086991004
1997	23.836584152094634
1998	24.04070242719734
1999	23.33064430185941
2000	24.004841882328083
2001	23.96610238401784
2002	23.44433719231238
2003	23.443091398382325
2004	21.990827051593243
2005	22.501909488427092
2006	23.493580585889127
2007	23.85033440052865
2008	25.70812028482053
2009	24.08702662339895
2010	23.531934242280116
2011	24.511290622038633
2012	24.266376699553398
2013	24.031684115080548
2014	23.447065031856557
2015	23.07435241696346