Year	Number of
1990	36.88
1991	37.56
1992	38.3
1993	39.09
1994	40.14
1995	41.12
1996	41.93
1997	42.86
1998	43.33
1999	43.7
2000	44.35
2001	44.49
2002	44.08
2003	44.3
2004	43.68
2005	43.92
2006	44.36
2007	44.27
2008	45.7
2009	46.14
2010	47.34
2011	48.83
2012	50.12
2013	51.23
2014	52.44
2015	53.72
2016	55.07