Year	Percent
1991	51.796
1992	48.631
1993	47.638
1994	49.405
1995	55.763
1996	57.877
1997	59.915
1998	60.818
1999	60.917
2000	64.956
2001	63.304
2002	64.377
2003	62.581
2004	63.636
2005	63.005
2006	67.244
2007	68.323
2008	67.977
2009	69.436
2010	69.633
2011	68.29
2012	71.042
2013	74.686
2014	76.652
2015	77.54
2016	79.902
2017	79.871
2018	80.319
2019	80.753
2020	81.239
2021	81.706
2022	82.151