Year	% of total
1992	16.760019522776574
1993	14.975789711191338
1994	17.578736211031174
1995	18.46914798206278
1996	16.487152003794165
1997	17.211563756801514
1998	17.041806763285024
1999	15.196495327102804
2000	12.685681639085894
2001	17.35599274235355
2002	20.540207457983193
2003	19.014074074074074
2004	19.4025827991453
2005	20.248465732087226
2006	20.03878035902851
2007	20.995102095647503
2008	22.160358974358978
2009	21.802612293144207
2010	22.90194076163611
2011	23.164523879285085
2012	24.310725980846463
2013	23.266636308439587
2014	23.26648275862069
2015	25.722663414634145
2016	27.228930158730158