Year	Number of
1990	66.54
1991	67.96
1992	70.36
1993	72.01
1994	75.12
1995	79.02
1996	82.16
1997	83.39
1998	85.32
1999	87.65
2000	90.97
2001	93.67
2002	96.33
2003	98.99
2004	102.64
2005	105.91
2006	109.65
2007	113.29
2008	118.2
2009	124.91
2010	130.96
2011	136.83
2012	142.17
2013	147.32
2014	152.21
2015	157.79
2016	164.61