Year	Number of
1990	34.91
1991	35.19
1992	35.45
1993	35.53
1994	35.72
1995	36.4
1996	37.27
1997	38.89
1998	40.23
1999	39.21
2000	38.06
2001	39.81
2002	42.03
2003	44.32
2004	47.47
2005	50.49
2006	51.61
2007	52.87
2008	55.43
2009	58.76
2010	60.1
2011	64.4
2012	66.91
2013	69.74
2014	72.86
2015	75.66
2016	78.03