Year	Percent
1980	0.90236
1981	0.79383
1982	0.63911
1991	2.38055
1992	1.69464
1993	1.34071
1994	1.35612
1997	1.17282
1998	1.25499
1999	1.59513
2000	1.53464
2001	3.10021
2002	3.32468
2003	2.44118
2004	2.22856
2012	2.98053
2013	3.15833
2014	2.97318
2015	3.30508
2016	2.48701
2017	2.33247