Year	% of total
1990	34.040014858116045
1991	34.97978045039382
1992	34.696836082669144
1993	34.008759362556546
1994	33.4908691035579
1995	32.971535404879525
1996	32.8012682762681
1997	32.509945671489966
1998	32.19669712890483
1999	31.83846425790375
2000	32.42233433533007
2001	32.187529000209494
2002	32.66534775333418
2003	32.400319612634775
2004	32.69939744580736
2005	32.373422931482835
2006	32.86159480201608
2007	32.74656060853631
2008	32.63978430657328
2009	31.055844014873163
2010	31.421404295512964
2011	31.280940442006425
2012	30.317317532863886
2013	30.241655720201546
2014	30.02800685005895
2015	29.269975498467993
2016	27.584662927642682