Year	Number of
1990	21.23
1991	21.89
1992	22.83
1993	23.94
1994	25.06
1995	26
1996	26.33
1997	26.2
1998	25.82
1999	25.82
2000	25.87
2001	27.1
2002	28.48
2003	29.64
2004	30.38
2005	31.26
2006	32.33
2007	32.88
2008	35.04
2009	39.05
2010	41.56
2011	43.52
2012	46.48
2013	50.57
2014	54.98
2015	58.84
2016	62.9