Year	% of total
1990	31.381728290387347
1991	30.725998725196217
1992	31.210331821153062
1993	27.435460451711158
1994	26.487777331544997
1995	28.61233169546437
1996	28.73964931054052
1997	30.58146920700371
1998	28.999801402665568
1999	27.550853109993195
2000	29.139205808276685
2001	26.929085336263753
2002	25.59374765801427
2003	27.615777785111217
2004	28.221319515120225
2005	24.764568486049846
2006	28.783345431224415
2007	29.281981126351592
2008	29.11665155134584
2009	32.620825732385676
2010	32.13823753404865
2011	36.027379158868996
2012	32.82754823542456
2013	33.523758813937384
2014	36.3315350391504
2015	36.134007871528
2016	37.210281456640764