Year	Number of
1990	270.3
1991	283.85
1992	301.57
1993	319.6
1994	344.45
1995	359.47
1996	379.37
1997	396.33
1998	406.81
1999	410.75
2000	411.54
2001	413.42
2002	418.49
2003	423.79
2004	425.17
2005	427.65
2006	430.18
2007	429.88
2008	427.16
2009	424.16
2010	423.44
2011	418.79
2012	423.18
2013	432.35
2014	436.27
2015	439.15
2016	442.98