Year	Number of
1990	68.18
1991	68.36
1992	68.92
1993	69.01
1994	69.61
1995	69.41
1996	68.93
1997	68.39
1998	68.38
1999	68.61
2000	68.94
2001	70.19
2002	71.37
2003	72.77
2004	74.02
2005	75.09
2006	76.55
2007	78.72
2008	81.51
2009	82.37
2010	83.76
2011	84.81
2012	86.4
2013	87.93
2014	90.44
2015	93.47
2016	97.4