Year	% of total
1990	23.12933476604474
1991	28.866109845608705
1992	31.08693269019952
1993	32.407407407407405
1994	32.407407407407405
1995	35.366631859844524
1996	40.89219330855018
1997	34.07822720598051
1998	34.098603470165045
1999	41.06554923675546
2000	35.1493848857645
2001	35.439795046968406
2002	33.513976041072446
2003	27.854436464400838
2004	29.509632224168126
2005	32.98788177880134
2006	30.056741865628684
2007	27.461012311901506
2008	25.96725584426163
2009	27.946127946127948
2010	31.774577131710448
2011	22.793498842836105
2012	25.672500069116143
2013	26.01014607285798
2014	32.89780541768821
2015	26.812076073946006