Year	Number of
1990	255.46
1991	263.23
1992	252.23
1993	241.57
1994	237.76
1995	238.12
1996	250.78
1997	265.15
1998	285.91
1999	300.63
2000	302.99
2001	296.75
2002	289.09
2003	282.94
2004	278.96
2005	278.17
2006	287.95
2007	296.9
2008	311.16
2009	329.36
2010	350.37
2011	368.23
2012	384.91
2013	410.23
2014	435.62
2015	463
2016	485.48