Year	% of total
1990	41.233946111490546
1991	41.25990318013398
1992	34.38581790282843
1993	33.95763193140559
1994	32.690777994151794
1995	32.242544526890555
1996	32.81851082550678
1997	33.3917159637773
1998	33.45832627204933
1999	33.95922521678173
2000	33.905982497800544
2001	33.2309867742627
2002	31.34501228028269
2003	30.37094007903904
2004	29.753067730006787
2005	27.699408070451955
2006	26.53642774714627
2007	25.27600472524771
2008	25.91029011788396
2009	25.53264987593132
2010	24.755958022089693
2011	24.007016383606615
2012	24.123743301442243
2013	24.237347427207325
2014	24.665054642500014
2015	25.18680402772849
2016	25.64325474940586