Year	Number of
1990	26.71
1991	27.55
1992	28.54
1993	29.76
1994	30.5
1995	32.58
1996	32.6
1997	35.7
1998	37.73
1999	36.58
2000	38.47
2001	41.68
2002	44.64
2003	45.9
2004	46.33
2005	49.09
2006	49.91
2007	51.63
2008	54.23
2009	56.25
2010	61.77
2011	64.76
2012	69.01
2013	71.77
2014	74.15
2015	76.34
2016	79.77