Year	% of total
1990	31.2600450016072
1991	28.42121782799749
1992	37.581011017498376
1993	39.27674535409342
1994	35.781310585498254
1995	35.65399210098351
1996	34.188557861683385
1997	35.71645415907711
1998	36.3053613053613
1999	33.780726888855376
2000	33.84468584850264
2001	34.003871146135765
2002	36.32004384162214
2003	36.96092619392185
2004	33.992534870015064
2005	34.868029370906925
2006	35.96427390009924
2007	36.442199029448915
2008	32.45929629855479
2009	31.286959702493444
2010	32.53152876038142
2011	33.34590009425071
2012	33.09107280679187
2013	30.843190587639953
2014	21.90176542562489
2015	29.594384828237835