Year	% of total
1990	18.499033248609432
1991	19.494489757945225
1992	18.089431225496106
1993	18.695288283625143
1994	20.551777234402927
1995	21.342740106096997
1996	21.295745847015077
1997	21.425265085332683
1998	26.489608959165185
1999	27.162013242485116
2000	21.680772562315813
2001	21.817606349053627
2002	21.070966940975662
2003	22.695920456789406
2004	22.823881519358636
2005	22.325567865317474
2006	24.728108335973644
2007	25.091680798209
2008	23.858263492645182
2009	23.49207541498186
2010	23.56734456585874
2011	22.12329970983355
2012	20.741372350765925
2013	20.19507721838562
2014	19.915746888486034
2015	22.184537479382563
2016	21.333289268694877