Year	Number of
1990	250.86
1991	258.04
1992	265.78
1993	274.17
1994	282.69
1995	291.43
1996	300.63
1997	309.72
1998	319.51
1999	329.85
2000	341.17
2001	353.97
2002	367.85
2003	383.65
2004	400.22
2005	417.69
2006	435.14
2007	453.08
2008	472.52
2009	493.18
2010	515.48
2011	539.21
2012	564.59
2013	590.7
2014	618.6
2015	648.52
2016	684.78