Year	Percent
1991	17.55
2006	31.11
2007	28.98
2008	23.41
2009	24.07
2010	27.31
2011	27.58
2012	28.01
2013	27.49
2014	27.52
2015	27.69
2016	25.41
2017	20.53
2018	18.4
2019	15.69
2020	15.87