Year	Number of
1990	79.66
1991	79.55
1992	80.17
1993	82.22
1994	85.36
1995	87.57
1996	91.1
1997	94.3
1998	98.89
1999	103.3
2000	107.02
2001	109.95
2002	112.39
2003	116.83
2004	122.37
2005	129.02
2006	135.42
2007	142.39
2008	149.71
2009	156.18
2010	163.05
2011	163.89
2012	165.33
2013	166.29
2014	165.09
2015	164.5
2016	163.75