Year	% of total
1991	44.808093833165074
1992	27.77051675394268
1993	26.992552623016557
1994	24.10065984273837
1995	24.28652078757475
1996	23.39934692773731
1997	23.625865322961214
1998	23.678683296515533
1999	22.849515526054375
2000	22.50334337028745
2001	22.887097682727866
2002	22.647395038329776
2003	22.20661622924737
2004	22.42532210750025
2005	21.936851230906253
2006	21.899032443336242
2007	21.76591089606056
2008	21.93288207055218
2009	22.914565444805007
2010	21.674376939387223
2011	22.110812588948335
2012	22.07705432840203
2013	21.61624815863363
2014	22.696744712746764
2015	23.182805158674302
2016	24.476256550072662