Year	Number of
1990	47.04
1991	47.96
1992	48.99
1993	50.1
1994	51.33
1995	52.7
1996	53.3
1997	53.98
1998	54.66
1999	55.31
2000	55.9
2001	57.63
2002	59.35
2003	61.19
2004	63.15
2005	65.32
2006	67.28
2007	69.4
2008	71.77
2009	74.35
2010	77.18
2011	78.31
2012	79.58
2013	80.88
2014	82.39
2015	84.15
2016	85.95