Year	Percent
1970	47.35921
1971	44.83571
1972	40.48058
1973	38.26594
1974	30.95793
1975	29.05815
1976	32.28706
1977	39.54755
1978	55.73309
1979	66.4326
1980	73.76143
1981	89.01185
1982	101.90394
1983	132.87721
1984	133.79324
1985	154.79063
1986	207.96232
1987	233.91465
1988	215.1627
1989	319.71356
1997	915.94975
1998	798.12652
1999	774.06669
2000	663.20196
2001	832.91372
2002	868.62672
2003	1380.76572
2004	1252.42461
2005	1001.6676
2006	927.32808
2007	645.99708
2008	457.79861
2009	183.09692
2010	37.62266
2011	31.56801
2012	33.06027
2013	32.24905
2014	40.50845
2015	47.71072
2016	52.28681