Year	% of total
1990	31.381728290387347
1991	30.72599872519621
1992	31.21033182115306
1993	27.435460451711158
1994	26.487777331544994
1995	28.612331695464366
1996	28.73964931054052
1997	30.58146920700371
1998	28.999801402665575
1999	27.550853109993202
2000	29.13920580827669
2001	26.92908533626376
2002	25.593747658014262
2003	27.61577778511122
2004	28.221319515120225
2005	24.764568486049846
2006	28.783345431224422
2007	29.281981126351596
2008	29.116651551345836
2009	32.620825732385676
2010	32.13823753404865
2011	36.02737915886901
2012	32.827548235424565
2013	33.5237588139374
2014	36.331535039150396
2015	36.134007871528
2016	37.21028145664077