Year	Number of
1990	25.55
1991	25.53
1992	25.42
1993	24.46
1994	25.48
1995	25.29
1996	23.9
1997	23.84
1998	23.44
1999	23.71
2000	24.3
2001	24.07
2002	25.19
2003	26.38
2004	27.67
2005	29.22
2006	29.39
2007	29.8
2008	32.16
2009	32.54
2010	33.4
2011	34
2012	33.26
2013	33.87
2014	36.55
2015	37.13
2016	37.74