Year	Percent
1991	39.993
1992	41.121
1993	40.758
1994	40.305
1995	40.725
1996	40.869
1997	40.58
1998	41.457
1999	41.759
2000	45.203
2001	45.754
2002	48.646
2003	49.488
2004	50.566
2005	51.779
2006	52.422
2007	52.823
2008	52.181
2009	53.658
2010	52.206
2011	51.004
2012	51.478
2013	51.405
2014	51.495
2015	52.196
2016	52.944
2017	53.197
2018	53.393
2019	53.598
2020	53.811
2021	54.025
2022	54.237