Year	Number of
1990	136.96
1991	140.14
1992	144.19
1993	150.04
1994	152.97
1995	157.59
1996	161.81
1997	167.37
1998	172.45
1999	176.62
2000	182.62
2001	187.05
2002	194.3
2003	200.88
2004	207.46
2005	212.16
2006	217.95
2007	224.6
2008	232.98
2009	242.71
2010	253.26
2011	262.1
2012	271.67
2013	282.06
2014	292.99
2015	304.82
2016	316.12