Year	Number of
1990	148.53
1991	157.87
1992	167.67
1993	178.22
1994	187.44
1995	195.72
1996	208.32
1997	219.73
1998	231.75
1999	238.24
2000	244.48
2001	251.71
2002	258.99
2003	268.84
2004	276.33
2005	284.88
2006	295.21
2007	307.38
2008	320.29
2009	331.62
2010	343.25
2011	353.99
2012	368.32
2013	385.83
2014	398.55
2015	410.92
2016	425.63