Year	Number of
1990	51.55
1991	52.41
1992	52.7
1993	51.7
1994	52.21
1995	51.51
1996	49.38
1997	47.02
1998	44.47
1999	42.09
2000	40.46
2001	40.57
2002	37.41
2003	36.07
2004	35.44
2005	34.64
2006	33.95
2007	33.95
2008	36.32
2009	36.79
2010	36.44
2011	36.08
2012	36.27
2013	40.39
2014	39.6
2015	39.93
2016	40.21