Year	% of total
1990	8.514737560991598
1991	9.173355728550733
1992	8.645065485280444
1993	9.678450313450792
1994	9.783487105448836
1995	9.73590790212647
1996	9.870589222961161
1997	10.90930605900437
1998	11.703617131692756
1999	12.646464851823685
2000	14.11527373210811
2001	12.701675695115112
2002	13.139802504612772
2003	18.753355697723954
2004	19.385044313009928
2005	18.6918959006921
2006	19.374118666728062
2007	19.48501212626882
2008	19.121740018664262
2009	18.58906698058939
2010	18.29239002614494
2011	21.88426577806653
2012	21.515040223015028
2013	20.41627209011074
2014	22.153980289571514
2015	22.793707491918372
2016	22.216277409189715