Year	Percent
1997	14.20519
1998	9.05096
1999	40.03483
2000	39.75178
2001	34.58881
2002	39.72187
2003	25.93183
2004	17.50681
2005	18.42324
2006	20.14267
2007	16.11719
2008	12.55357
2009	19.52513
2010	28.43193
2011	22.81596
2012	22.56199
2013	14.72315
2014	23.16238
2015	16.65735
2016	14.93084
2017	11.64587
2018	8.67883
2019	11.59292
2020	19.03897
2021	16.19709