Year	% of total
1990	57.3362774069493
1991	55.60705820630379
1992	48.63433902881565
1993	48.95255718759944
1994	50.10979041324993
1995	49.90568423710447
1996	50.71941233160346
1997	48.92139743621922
1998	46.22191824394886
1999	46.055059454503
2000	44.86688535388418
2001	43.944645109492576
2002	45.66569841680998
2003	47.84634162523443
2004	48.85248076888233
2005	50.355897313978986
2006	51.52550362368977
2007	49.739712747231145
2008	53.95801259558693
2009	51.47401758533442
2010	53.59444365537021
2011	55.398920377885894
2012	55.670661740168
2013	53.60047088093058
2014	53.36324582108069
2015	53.351005112637075
2016	52.13294625774325