Year	Number of
1990	45.75
1991	47.95
1992	50.52
1993	53.44
1994	56.39
1995	59.11
1996	60.84
1997	62.26
1998	63.61
1999	64.93
2000	66.35
2001	66.5
2002	66.78
2003	67.05
2004	67.55
2005	68.27
2006	70.25
2007	72.51
2008	75.2
2009	78.1
2010	81.28
2011	83.63
2012	86.35
2013	88.94
2014	91.87
2015	95.06
2016	98.3