Year	% of total
1990	33.286766189821506
1991	34.48270621402194
1992	34.9859736650143
1993	34.33908029277523
1994	33.72983631884395
1995	33.25604815946899
1996	32.98757853535568
1997	32.44033343140289
1998	32.4480017355328
1999	32.16639499902097
2000	32.962666517728735
2001	32.760635830804176
2002	33.37892459887297
2003	33.191161180375865
2004	33.54273399627332
2005	33.355752200594544
2006	33.97408160304555
2007	33.95877705603331
2008	34.08237143926638
2009	32.62372770977278
2010	33.08073290898749
2011	33.06899633806198
2012	32.41673818483517
2013	32.24085833478546
2014	32.065876261684835
2015	31.528622433861393
2016	29.73329289903362