Year	Number of
1990	323.21
1991	318.22
1992	313.37
1993	312.72
1994	307.52
1995	303.34
1996	295.58
1997	292.68
1998	291.97
1999	291.29
2000	299.84
2001	297.97
2002	302.02
2003	307.94
2004	315.36
2005	323.56
2006	330.97
2007	341.28
2008	349.89
2009	358.71
2010	374.06
2011	383.05
2012	399.67
2013	414.76
2014	427.06
2015	439.75
2016	455.7