Year	Number of
1990	249.95
1991	258.7
1992	267.95
1993	277.99
1994	286.51
1995	299.18
1996	312.99
1997	324.88
1998	330.14
1999	337.89
2000	352.02
2001	356.38
2002	370.94
2003	383.55
2004	392.55
2005	400.12
2006	406.3
2007	410.63
2008	429.86
2009	427.74
2010	440.32
2011	452.58
2012	460.83
2013	472.66
2014	487.49
2015	503.41
2016	520.05