Year	Number of
1990	65.85
1991	68.56
1992	71.19
1993	73.79
1994	76.35
1995	78.95
1996	82.7
1997	86.48
1998	90.37
1999	94.25
2000	98.24
2001	102.99
2002	107.83
2003	112.87
2004	117.92
2005	123.09
2006	128.77
2007	134.3
2008	140.03
2009	145.84
2010	151.91
2011	158.55
2012	165.31
2013	171.87
2014	178.59
2015	185.55
2016	195.33