Year	Percent
1990	29.02516
1991	44.76957
1992	42.28612
1993	56.54885
1994	37.75545
1995	37.76038
1996	34.63274
1997	33.2717
1998	38.76808
1999	44.08537
2000	37.11216
2001	40.24149
2002	41.56116
2003	40.23146
2004	39.84216
2005	40.1542
2006	42.8795
2007	49.2018
2008	51.27901
2009	46.8327
2010	49.89164
2011	56.99147
2012	55.60377
2013	56.61406
2014	57.9109
2015	54.8878
2016	55.80196
2017	58.24954