Year	Number of
1990	252.85
1991	264.92
1992	277.98
1993	292.37
1994	308.64
1995	324.98
1996	338.83
1997	352.26
1998	363.43
1999	375.19
2000	381.18
2001	382.58
2002	385.52
2003	389.74
2004	395.68
2005	404.87
2006	413.65
2007	420.73
2008	430.43
2009	441.16
2010	453.15
2011	464.53
2012	471.29
2013	486.92
2014	501.49
2015	517.63
2016	535.89