Year	Number of
1990	25.62
1991	26.49
1992	27.45
1993	28.63
1994	29.99
1995	31.55
1996	33.17
1997	34.87
1998	37.34
1999	41.22
2000	43.76
2001	46.37
2002	49.28
2003	52.11
2004	53.71
2005	55.81
2006	56.89
2007	58.17
2008	59.65
2009	61.97
2010	66.84
2011	71.56
2012	74.82
2013	78.26
2014	81.54
2015	85.62
2016	90.65