Year	Number of
1990	74.59
1991	76.87
1992	79.02
1993	82.95
1994	86.75
1995	90.43
1996	95.75
1997	98.03
1998	100.78
1999	105.65
2000	112.44
2001	118.79
2002	124.81
2003	132.11
2004	138.69
2005	145.03
2006	147.77
2007	150.36
2008	152.85
2009	155.74
2010	159.71
2011	165.43
2012	171.24
2013	176.55
2014	181.59
2015	186.76
2016	192.04