Year	Number of
1990	40.75
1991	41.24
1992	40.93
1993	40.73
1994	41.11
1995	41.43
1996	42.23
1997	43.3
1998	44.58
1999	46.01
2000	47.72
2001	49.49
2002	51.69
2003	53.84
2004	56.09
2005	58.23
2006	59.89
2007	61.58
2008	63.23
2009	64.62
2010	66.41
2011	67.8
2012	69.65
2013	71.53
2014	73.56
2015	75.91
2016	78.38