Year	Number of
1990	32.63
1991	33.76
1992	34.48
1993	35.55
1994	36.66
1995	37.86
1996	39.71
1997	40.41
1998	41.18
1999	41.92
2000	42.98
2001	44.31
2002	45.02
2003	45.42
2004	46.3
2005	46.93
2006	47.58
2007	48.04
2008	48.66
2009	49.1
2010	49.17
2011	49.98
2012	51.83
2013	53.43
2014	55.52
2015	57.74
2016	59.92