Year	Number of
1990	49.58
1991	54.42
1992	58.09
1993	61.13
1994	63.61
1995	64.55
1996	65.76
1997	66.59
1998	66.28
1999	67.86
2000	69.1
2001	69.79
2002	72.82
2003	74.24
2004	73.22
2005	74.41
2006	74.47
2007	73.07
2008	76.21
2009	81.77
2010	86.27
2011	89.64
2012	98.03
2013	101.77
2014	107.18
2015	111.32
2016	115.72