Year	Number of
1990	626.6
1991	610.59
1992	595.9
1993	575.79
1994	553.53
1995	546.08
1996	531.74
1997	536.98
1998	542.38
1999	532.39
2000	524.07
2001	509.86
2002	499.32
2003	490.59
2004	484.9
2005	487.58
2006	482.63
2007	482.77
2008	476.45
2009	471.55
2010	467.31
2011	458.82
2012	454.14
2013	450.56
2014	448.1
2015	455.16
2016	464.04