Year	Number of
1990	155.2
1991	156.08
1992	155.99
1993	155.33
1994	154.78
1995	154.85
1996	156.67
1997	159.41
1998	163.39
1999	168.98
2000	176.46
2001	185.95
2002	198.15
2003	212.29
2004	227.19
2005	242.26
2006	253.39
2007	263.77
2008	274.05
2009	284.84
2010	296.75
2011	305.82
2012	315.83
2013	326.54
2014	337.89
2015	349.85
2016	362.38