Year	Number of
1990	53.78
1991	54.84
1992	56.71
1993	58.82
1994	59.87
1995	63.32
1996	66.41
1997	69.21
1998	68.64
1999	72.91
2000	76.55
2001	76.09
2002	77.02
2003	80.35
2004	82.19
2005	83.63
2006	81.96
2007	82.82
2008	83.97
2009	86.39
2010	88.77
2011	93.74
2012	97.72
2013	103.77
2014	109.54
2015	115.99
2016	122.48