Year	Percent
1980	7.86868
1981	12.2168
1982	19.27739
1983	13.95848
1984	12.73393
1985	24.84641
1987	15.88953
1988	16.27235
1989	13.07757
1990	10.74388
1991	13.01125
2002	3.92997
2003	3.33399
2004	2.43386
2005	1.99302
2006	1.75051
2007	1.95983
2008	2.0105
2009	1.99221
2010	1.49994