Year	Number of
1990	210.32
1991	216.84
1992	223.5
1993	229.14
1994	234.69
1995	241.86
1996	247.52
1997	253.69
1998	260.13
1999	265.02
2000	269.99
2001	278.24
2002	288.54
2003	297.42
2004	308.08
2005	319.47
2006	330.58
2007	341.04
2008	350.64
2009	361.93
2010	373.32
2011	386.38
2012	399.41
2013	411.62
2014	424.9
2015	438.51
2016	454.21