Year	Number of
1990	42.84
1991	47.71
1992	52.11
1993	57.47
1994	63.04
1995	69.41
1996	76.01
1997	82.57
1998	90.04
1999	97.97
2000	108.09
2001	117.81
2002	128.88
2003	142.41
2004	153.86
2005	166.94
2006	176.19
2007	184.72
2008	194.51
2009	204.5
2010	216.83
2011	226.74
2012	233.73
2013	243.49
2014	253.9
2015	264.68
2016	277.3