Year	Calculated Units per Year
1987
1988
1989	240
1990	240
1991	240
1992	205
1993	205
1994	205
1995	217
1996	195
1997	195
1998	190
1999	197
2000	164
2001	132
2002	171
2003	148
2004	40
2005	37
2006	58
2007	62
2008	43
2009	16
2010	16
2011	16
2012	18
2013	18
2014	18
2015	18
2016	18
Source:	derived data