Year	Number of
1990	26.89
1991	29.58
1992	32.47
1993	34.6
1994	37.37
1995	40.72
1996	44.03
1997	48.01
1998	49.08
1999	49.5
2000	48.69
2001	48.63
2002	50.12
2003	48.37
2004	48.97
2005	49.41
2006	50.45
2007	52.06
2008	52.79
2009	55.05
2010	55.87
2011	56.92
2012	59.91
2013	62.13
2014	64.43
2015	66.73
2016	68.9