Year	Number of
1990	54.46
1991	57.05
1992	59.47
1993	61.93
1994	64.56
1995	67.25
1996	70.03
1997	72.96
1998	76.21
1999	79.51
2000	82.89
2001	86.04
2002	89.32
2003	93.2
2004	97.09
2005	100.97
2006	104.39
2007	107.99
2008	112.07
2009	116.26
2010	120.61
2011	125.17
2012	129.92
2013	134.63
2014	139.72
2015	145.04
2016	150.19