Year	Percent
1990	21.52087
1995	19.08248
1996	19.79847
1997	19.28499
1998	17.73499
1999	17.12535
2009	16.02451
2010	15.49918
2011	15.98578
2012	16.62894
2013	17.24117
2014	17.37814
2015	16.74526
2016	16.64981