Year	Number of
1990	55.63
1991	53.5
1992	54.26
1993	52.84
1994	52.41
1995	49.92
1996	50.56
1997	50.95
1998	51.34
1999	47.8
2000	46.6
2001	43.98
2002	44.38
2003	42.01
2004	40.26
2005	40.8
2006	40.6
2007	39.88
2008	39.6
2009	39.11
2010	41.67
2011	42.38
2012	43.04
2013	43.65
2014	44.42
2015	45.18
2016	46.27