Year	Number of
1990	161.42
1991	161.47
1992	161.95
1993	166.05
1994	165.91
1995	167.04
1996	169.78
1997	171.26
1998	173.61
1999	173.73
2000	175.17
2001	177.1
2002	181.26
2003	186.75
2004	190.21
2005	193.89
2006	197.26
2007	200.7
2008	206.77
2009	214.73
2010	223.7
2011	232.75
2012	243.14
2013	253.98
2014	265.89
2015	278.89
2016	292.59