Year	Number of
1990	36.65
1991	37.37
1992	37.65
1993	38.85
1994	39.97
1995	41.02
1996	42.36
1997	40.18
1998	39.38
1999	39.2
2000	38.53
2001	37.02
2002	35.3
2003	35.21
2004	34.51
2005	34.77
2006	36
2007	36.13
2008	36.09
2009	36.61
2010	36.3
2011	35.49
2012	34.92
2013	34.75
2014	35.55
2015	36.16
2016	37.04