Year	Number of
1990	46.28
1991	44.03
1992	44.82
1993	47.13
1994	48.41
1995	49.25
1996	50.46
1997	52.51
1998	55.28
1999	57.9
2000	60.34
2001	62.18
2002	63.66
2003	66
2004	66.24
2005	66.25
2006	68.42
2007	70.09
2008	71.94
2009	72.87
2010	74.5
2011	76.2
2012	77.55
2013	77.79
2014	79.22
2015	80.02
2016	80.69