Year	Units
1973-01-01	1177600900.17417
1974-01-01	1415484521.89754
1975-01-01	1384409618.00736
1976-01-01	1525895147.63486
1977-01-01	1614392491.44277
1978-01-01	1656179976.69624
1979-01-01	1906433120.40193
1980-01-01	2014179681.16005
1981-01-01	2268918555.55475
1982-01-01	2193094748.41876
1983-01-01	2291919507.56888
1984-01-01	2516586363.18491
1985-01-01	2701250457.23325
1986-01-01	2638978316.84871
1987-01-01	2740104988.02109
1988-01-01	3023879082.09366
1989-01-01	3321671765.87720
1990-01-01	3440013420.25004
1991-01-01	3456122565.15725
1992-01-01	3510211744.41449
1993-01-01	3470820040.26075
1994-01-01	4003332049.44660
1995-01-01	4054835892.62831
1996-01-01	3748534643.33333
1997-01-01	4092796778.33333
1998-01-01	4157211125.00000
1999-01-01	4360112545.83333
2000-01-01	4968273996.66667
2001-01-01	5077831808.33333
2002-01-01	4955031533.33333
2003-01-01	5047610966.66667
2004-01-01	5896179800.00000
2005-01-01	6379331841.66667
2006-01-01	7297933941.66667
2007-01-01	7698064408.33333
2008-01-01	9611820775.00000
2009-01-01	7937583066.66667
2010-01-01	9164620600.00000
2011-01-01	9943398875.00000
2012-01-01	10109889116.66670
2013-01-01	10254365533.33330