Year	% of total
1990	34.72676908345915
1991	35.56495169765572
1992	35.26135618934215
1993	34.58413069420373
1994	34.03765676453584
1995	33.59475136402168
1996	33.46917210353654
1997	33.18576807125048
1998	32.91448618930779
1999	32.548048736529246
2000	33.10124460725185
2001	32.89146659138012
2002	33.446187266315434
2003	33.2801701877932
2004	33.56604453689052
2005	33.33747308382158
2006	33.96675664364267
2007	33.863775701567214
2008	33.95563188468529
2009	32.611000914750505
2010	33.11149837186602
2011	33.09176345890606
2012	32.16423584590117
2013	32.14572288960934
2014	32.14230004474003
2015	31.503351266409467
2016	29.90892710815318