Year	% of total
1990	23.571064326224096
1991	23.500544668108436
1992	18.52334106795092
1993	17.933856018085052
1994	17.276200297205673
1995	16.675102544095044
1996	16.7109201358088
1997	16.607589702548466
1998	16.564676183877353
1999	17.20714909617158
2000	17.338395109002878
2001	17.400840415871762
2002	16.753679086455655
2003	16.49637012129947
2004	15.606885411026703
2005	15.095631411467378
2006	14.69096426153885
2007	14.555156804970657
2008	14.505796968438467
2009	13.903566059758033
2010	13.93372684948141
2011	13.663741788958221
2012	13.481337283711225
2013	13.58163588071985
2014	13.931872328227119
2015	13.942022065326569
2016	14.263323995455366