Year	Number of
1990	504.58
1991	496.93
1992	512.69
1993	525.01
1994	549.4
1995	541.57
1996	523.96
1997	499.65
1998	473.39
1999	453.48
2000	437.33
2001	430.1
2002	429.54
2003	431.25
2004	434.9
2005	448.39
2006	456.4
2007	462.61
2008	453.36
2009	445.82
2010	440.2
2011	442.71
2012	441.21
2013	438.66
2014	438.36
2015	438.27
2016	437.93