Year	Number of
1990	28.69
1991	28.53
1992	28.94
1993	29.37
1994	30.07
1995	30.04
1996	29.67
1997	29.61
1998	32.44
1999	33.97
2000	39.27
2001	39.05
2002	40.53
2003	44.08
2004	44.3
2005	45.08
2006	44.12
2007	44.33
2008	46.37
2009	45.73
2010	46.45
2011	44.55
2012	44.15
2013	44.04
2014	42.95
2015	41.85
2016	40.71