Year	% of total
1992	29.330016250769898
1993	28.355920793232173
1994	25.115035065672785
1995	25.109648998873592
1996	24.134352368576664
1997	24.206604115681767
1998	23.97129058781439
1999	22.95526522951311
2000	22.599193811701607
2001	22.761477236957827
2002	22.496377733684636
2003	22.096078196403283
2004	22.349397071209882
2005	21.780271763092035
2006	21.676501119399987
2007	21.46871565321335
2008	21.603402927084836
2009	22.648638935984405
2010	21.295563353441423
2011	21.82383646821022
2012	21.843597871584816
2013	21.478702062690253
2014	22.636939954508488
2015	23.04853219676952
2016	24.328974605886845