Year	% of total
1992	35.66171491339816
1993	35.460365540415694
1994	36.11730111135003
1995	35.778757598347504
1996	36.16674253558346
1997	34.139758254481315
1998	33.54521807456397
1999	33.83516889023043
2000	33.739203817705786
2001	32.81123762325026
2002	32.70497516066474
2003	32.67886378985557
2004	32.158074965833116
2005	31.991172940198037
2006	33.112203602896
2007	32.36465555161437
2008	32.712817025511505
2009	31.050875355836094
2010	31.277759555680444
2011	31.04734232251998
2012	33.61578120638121
2013	32.22824577541634
2014	31.70282281750175
2015	33.15691656914967
2016	33.10086814901827