Year	Number of
1990	262.59
1991	269.09
1992	276.46
1993	284.41
1994	292.8
1995	301.87
1996	311.69
1997	322.54
1998	334.1
1999	346.23
2000	359.18
2001	369.62
2002	380.56
2003	392.06
2004	404.32
2005	417.63
2006	426.68
2007	435.97
2008	446.03
2009	456.76
2010	468.32
2011	480.27
2012	493.68
2013	508.01
2014	523.1
2015	538.82
2016	555.55