Year	Number of
1990	36.91
1991	39.01
1992	41.16
1993	43.66
1994	46.44
1995	49.36
1996	51.75
1997	54.72
1998	56.25
1999	57.3
2000	57.45
2001	58.17
2002	60.03
2003	59.57
2004	61.17
2005	62.67
2006	64.44
2007	66.7
2008	68.61
2009	71.8
2010	73.82
2011	75.87
2012	79.64
2013	82.66
2014	86.11
2015	89.83
2016	93.47