Year	Number of
1990	181.13
1991	186.04
1992	185.28
1993	185.75
1994	186.65
1995	188.63
1996	191.18
1997	194.04
1998	197.55
1999	202.03
2000	207.75
2001	214.43
2002	221.93
2003	230.21
2004	239.29
2005	249.26
2006	258.23
2007	268.88
2008	280.96
2009	293.18
2010	306.59
2011	321.24
2012	337.21
2013	354.53
2014	372.59
2015	392.11
2016	411.46