Year	% of total
1992	22.475420576650365
1993	23.35457790019133
1994	23.573806248444033
1995	23.986529164442086
1996	25.431829907375143
1997	24.018840164286882
1998	23.335043969495782
1999	24.59612247716146
2000	23.06003503761193
2001	23.257551649761936
2002	23.971379083704583
2003	25.09117662569417
2004	25.002469818990644
2005	25.642421518253954
2006	24.530436469718985
2007	23.672628606305622
2008	23.66337579108518
2009	22.945784418381415
2010	23.888865571172637
2011	23.393431602219426
2012	22.13938744109587
2013	21.539403704791074
2014	20.87920702490845
2015	21.873897752787585
2016	21.751248748063084