Year	Number of
1990	277.46
1991	277.28
1992	278.39
1993	280.74
1994	284.11
1995	288.8
1996	288.71
1997	286.61
1998	285.76
1999	285.76
2000	287.49
2001	288.34
2002	289.15
2003	294.05
2004	297.96
2005	302.4
2006	310.6
2007	319.67
2008	330.61
2009	341.77
2010	354.16
2011	368.47
2012	384.5
2013	401.22
2014	418.73
2015	437.69
2016	456.59