Year	Number of
1990	76.73
1991	78.92
1992	81.25
1993	83.74
1994	86.39
1995	89.32
1996	92
1997	94.97
1998	98.29
1999	101.63
2000	105.13
2001	108.44
2002	112.03
2003	116.11
2004	120.44
2005	125.17
2006	129.18
2007	133.3
2008	137.94
2009	142.86
2010	148.27
2011	152.52
2012	157.31
2013	162.47
2014	168
2015	173.93
2016	180.08