Year	% of total
1990	41.405404826305876
1991	41.304898528299915
1992	34.24910059194155
1993	33.76449199084175
1994	32.45838801224473
1995	31.977609872800098
1996	32.523408902723524
1997	33.09640889534944
1998	33.1344749986536
1999	33.64597098550431
2000	33.62011646405715
2001	32.94660113649279
2002	31.14875818129252
2003	30.018875790343074
2004	29.43020393821001
2005	27.39306930431257
2006	26.204959441653433
2007	24.827298270643354
2008	25.473868925673592
2009	25.098264433713574
2010	24.369743913506827
2011	23.62644841806919
2012	23.799194756111046
2013	23.880703893090036
2014	24.32380551457073
2015	24.871396205329336
2016	25.32795638890244