Year	Number of
1990	52.23
1991	53.98
1992	55.76
1993	57.81
1994	59.86
1995	61.96
1996	63.65
1997	65.38
1998	67.28
1999	69.21
2000	71.56
2001	72.69
2002	73.76
2003	74.9
2004	76.03
2005	77.49
2006	79.38
2007	81.1
2008	82.44
2009	83.52
2010	84.47
2011	87.18
2012	90.46
2013	93.95
2014	97.32
2015	100.77
2016	104.28