Year	Number of
1990	39.75
1991	40.75
1992	41.79
1993	42.69
1994	43.82
1995	45.09
1996	46.42
1997	47.77
1998	48.99
1999	49.96
2000	50.25
2001	51.07
2002	51.49
2003	52.04
2004	53.21
2005	53.77
2006	53.74
2007	53.71
2008	54.25
2009	55.94
2010	57.13
2011	59.07
2012	60.61
2013	61.46
2014	61.81
2015	62
2016	62.5