Year	Number of
1990	34.71
1991	34.93
1992	35.09
1993	35.28
1994	35.17
1995	34.7
1996	33.6
1997	32.98
1998	33.23
1999	33.99
2000	34.97
2001	35.73
2002	36.74
2003	38.09
2004	39.47
2005	40.79
2006	41.4
2007	41.74
2008	42.48
2009	43.22
2010	43.91
2011	43.5
2012	43.09
2013	42.64
2014	42.24
2015	42.03
2016	42.04