Year	Number of
1990	25.58
1991	26.8
1992	28.03
1993	29.21
1994	30.14
1995	30.56
1996	30.5
1997	30.35
1998	29.98
1999	29.55
2000	29.32
2001	29.84
2002	31.28
2003	33
2004	33
2005	32.2
2006	32.13
2007	32.67
2008	33.91
2009	35.22
2010	36.88
2011	37.64
2012	38.64
2013	39.75
2014	41.39
2015	43.35
2016	44.61