Year	Number of
1990	141.56
1991	146.54
1992	152.1
1993	158.15
1994	164.62
1995	171.27
1996	177.08
1997	182.53
1998	188.07
1999	192.43
2000	197.44
2001	204.49
2002	215.46
2003	215.5
2004	217.28
2005	221.16
2006	225.41
2007	229.62
2008	235.93
2009	244.27
2010	254.99
2011	265.35
2012	276.53
2013	288.48
2014	301.45
2015	315.39
2016	330.31