Year	Percent
1991	39.37
1992	40.517
1993	41.413
1994	42.54
1995	43.294
1996	42.711
1997	41.683
1998	40.707
1999	40.142
2000	39.995
2001	40.038
2002	40.178
2003	40.407
2004	40.725
2005	41.123
2006	41.635
2007	42.34
2008	43.185
2009	43.942
2010	44.337
2011	45.254
2012	45.56
2013	45.762
2014	45.748
2015	45.554
2016	45.15
2017	44.458
2018	43.565
2019	42.588
2020	41.64
2021	40.754
2022	39.989