Year	Number of
1990	68.47
1991	68.18
1992	68.73
1993	69.25
1994	70.16
1995	71.54
1996	73.99
1997	75.49
1998	80
1999	84.41
2000	88.29
2001	89.15
2002	90.92
2003	95.68
2004	101.29
2005	107.02
2006	113.89
2007	120.16
2008	125.43
2009	131.39
2010	136.68
2011	141.93
2012	150.37
2013	158.81
2014	167.77
2015	176.39
2016	184.12