Year	Number of
1990	90.92
1991	96
1992	105.26
1993	114.9
1994	123.53
1995	131.16
1996	137.28
1997	140.34
1998	144.39
1999	145.42
2000	147.22
2001	150.27
2002	156.24
2003	162.76
2004	166.07
2005	167.73
2006	168.86
2007	172.14
2008	175.3
2009	180.05
2010	187.54
2011	193.36
2012	201.01
2013	209.46
2014	216.26
2015	221.69
2016	226.36