Year	Number of
1990	249.55
1991	246.33
1992	242.79
1993	241.73
1994	237.9
1995	235
1996	228.75
1997	225.66
1998	223.41
1999	225.03
2000	232.02
2001	232.93
2002	238.26
2003	242.08
2004	247.65
2005	254.43
2006	259.47
2007	267.27
2008	274.29
2009	282.55
2010	290.96
2011	298.56
2012	305.99
2013	313.64
2014	321.74
2015	331.27
2016	342.41