Year	Number of
1990	399.12
1991	404.18
1992	411.45
1993	413.14
1994	416.36
1995	422.86
1996	422.28
1997	422.96
1998	419.43
1999	412.97
2000	411.98
2001	415.19
2002	416.54
2003	422.09
2004	421.53
2005	420.38
2006	418.37
2007	421.3
2008	427.03
2009	437.06
2010	452.41
2011	473.31
2012	499.65
2013	522.09
2014	550.61
2015	586.3
2016	619.22