Year	Percent
1991	15.888
1992	15.626
1993	15.954
1994	15.731
1995	15.847
1996	15.693
1997	15.711
1998	15.924
1999	16.17
2000	16.472
2001	16.933
2002	17.281
2003	17.684
2004	18.18
2005	19.232
2006	19.205
2007	20.334
2008	20.39
2009	20.985
2010	21.671
2011	22.621
2012	23.307
2013	24.321
2014	26.027
2015	26.503
2016	27.131
2017	27.618
2018	28.355
2019	29.054
2020	29.831
2021	30.572
2022	31.296