Year	Number of
1990	236.13
1991	240.84
1992	249.97
1993	257.89
1994	265.26
1995	271.32
1996	281.16
1997	291.57
1998	290.93
1999	290.31
2000	292.08
2001	280.38
2002	282.64
2003	281.32
2004	284.75
2005	293.39
2006	296.03
2007	307.4
2008	313.58
2009	326.01
2010	341.07
2011	351.87
2012	363.23
2013	380.04
2014	409.1
2015	445.54
2016	474.44