Year	Number of
1990	41.85
1991	43.18
1992	44.68
1993	46.46
1994	48.06
1995	49.98
1996	51.21
1997	53.63
1998	55.85
1999	58.15
2000	60.75
2001	62.03
2002	63.56
2003	64.76
2004	65.72
2005	66.28
2006	66.41
2007	68.59
2008	69.27
2009	70.07
2010	70.66
2011	73.56
2012	75.09
2013	76.71
2014	79.17
2015	82.2
2016	85.43