Year	Number of
1990	432.61
1991	431.53
1992	427.38
1993	433.09
1994	441.23
1995	436.17
1996	427.94
1997	419.43
1998	413.49
1999	415.2
2000	411.02
2001	409.63
2002	405.08
2003	407.65
2004	411.05
2005	415.38
2006	420.1
2007	422.75
2008	427.93
2009	433.72
2010	441.72
2011	450.33
2012	458.45
2013	464.66
2014	471.41
2015	479.64
2016	490.16