Year	Percent
1991	33.902
1992	35.055
1993	35.176
1994	35.075
1995	35.532
1996	35.503
1997	36.234
1998	36.673
1999	38.734
2000	39.961
2001	38.834
2002	39.052
2003	39.265
2004	40.318
2005	41.161
2006	41.371
2007	42.488
2008	43.178
2009	42.954
2010	43.447
2011	43.446
2012	43.416
2013	43.704
2014	44.2
2015	44.294
2016	44.155
2017	44.434
2018	44.764
2019	44.779
2020	44.708
2021	44.596
2022	44.47