Year	Number of
1990	47.8
1991	46.67
1992	47.14
1993	47.38
1994	47.85
1995	49.3
1996	47.14
1997	44.78
1998	42.86
1999	41.4
2000	41.17
2001	40.07
2002	38.31
2003	37.74
2004	37.26
2005	36.86
2006	36.58
2007	36.45
2008	36.98
2009	37.08
2010	36.81
2011	37.73
2012	38.73
2013	39.94
2014	40.99
2015	42.12
2016	43.36