Year	% of total
1990	24.65118303565986
1991	24.254869791180525
1992	19.03497301533581
1993	18.795101457971963
1994	18.154685357965352
1995	17.413962469493725
1996	17.63412971167681
1997	17.54510437466744
1998	17.46990630902587
1999	17.83908653248775
2000	18.172545226881567
2001	18.252523382610033
2002	17.5692229240805
2003	17.25653099823434
2004	16.128833081967635
2005	15.343284079463684
2006	14.833004433692235
2007	14.64879366260728
2008	14.714119843768934
2009	14.179800085508925
2010	14.348704735883306
2011	14.164956047815918
2012	14.092927412858392
2013	14.092628500651548
2014	14.578094091979763
2015	14.525590475323966
2016	14.839989741778952