Year	Percent
1988	27.69921
1989	5.34083
1990	10.01254
1991	1.94732
1992	3.71824
1993	4.34791
1994	21.13368
1995	16.53204
1996	19.91825
1997	19.93483
1998	20.45084
1999	16.6091
2000	12.85539
2001	10.10486
2002	12.00543
2003	13.64234
2004	14.04176
2005	33.96828
2006	46.88047
2007	60.66346
2008	40.74828
2009	31.44598
2010	21.00094
2011	20.85932
2012	14.3277
2013	15.47483
2014	16.93751
2015	19.90161
2016	23.2479