Year	Number of
1990	19.15
1991	20.23
1992	21.46
1993	22.73
1994	24.09
1995	25.52
1996	26.27
1997	26.95
1998	27.71
1999	28.48
2000	29.32
2001	31.56
2002	34.06
2003	36.85
2004	39.87
2005	43.13
2006	46.43
2007	50.01
2008	53.86
2009	57.94
2010	62.21
2011	67.11
2012	72.36
2013	77.98
2014	84.15
2015	90.97
2016	98.09