Year	% of total
1990	79.54666069169295
1991	77.97045484055649
1992	76.33260852454697
1993	73.63522626507172
1994	74.973446923679
1995	72.34771300496335
1996	74.54001308532028
1997	71.22026290677053
1998	65.27268738027027
1999	64.69873886384373
2000	62.11834589667623
2001	60.320886890168026
2002	63.9624498722351
2003	66.52389448130486
2004	67.2246299655794
2005	68.89675850654554
2006	69.8588665222914
2007	65.74921736160208
2008	73.89696719514475
2009	68.17360226612168
2010	71.97403988642061
2011	73.84299644993821
2012	73.48709892815529
2013	70.19470922608089
2014	69.0887730140514
2015	68.84775406733945
2016	66.52162124664665