Year	Number of
1990	30.46
1991	33.87
1992	34.38
1993	36.45
1994	39.85
1995	43.34
1996	47.91
1997	50.43
1998	51.75
1999	53.38
2000	56.64
2001	60.09
2002	63.77
2003	64.86
2004	66.39
2005	68.23
2006	73.94
2007	76.36
2008	79.6
2009	82.29
2010	83.31
2011	86.69
2012	88.09
2013	89.53
2014	93
2015	93.19
2016	94.51