Year	Percent
1991	39.242
1992	39.209
1993	39.194
1994	39.462
1995	39.653
1996	39.837
1997	40.027
1998	40.179
1999	40.391
2000	40.64
2001	40.961
2002	41.342
2003	41.615
2004	41.947
2005	42.333
2006	42.654
2007	42.96
2008	43.259
2009	43.554
2010	43.843
2011	44.183
2012	44.393
2013	44.451
2014	44.491
2015	44.569
2016	44.606
2017	44.72
2018	44.841
2019	44.966
2020	45.095
2021	45.225
2022	45.354