Year	Number of
1990	9.85
1991	10.41
1992	10.97
1993	11.56
1994	12.16
1995	12.8
1996	13.53
1997	14.26
1998	15.04
1999	15.8
2000	16.57
2001	17.42
2002	18.33
2003	19.23
2004	20.15
2005	21.12
2006	22.25
2007	23.41
2008	24.66
2009	26.03
2010	27.55
2011	28.63
2012	29.89
2013	31.28
2014	32.75
2015	34.26
2016	35.86