Year	Percent
1999	24.57
2000	21.12
2001	20.07
2002	27.93
2003	24.93
2004	28.3
2005	28.29
2007	31.51
2008	37.55
2009	44.28
2010	41.54
2011	41.87
2012	38.23
2013	41.03
2014	38.19
2015	36.87
2016	36.03
2017	28.89
2018	29.9
2019	30.35
2020	39.43