Year	Number of
1990	37.75
1991	38.71
1992	39.72
1993	40.77
1994	41.89
1995	43.11
1996	44.54
1997	46.06
1998	47.63
1999	49.33
2000	51.18
2001	52.66
2002	54.23
2003	55.93
2004	57.76
2005	59.75
2006	61.55
2007	63.46
2008	65.57
2009	67.85
2010	70.33
2011	72.78
2012	75.42
2013	78.22
2014	81.21
2015	84.42
2016	88.08