Year	Number of
1990	28.18
1991	30.62
1992	32.84
1993	35.09
1994	37.52
1995	40.13
1996	42.31
1997	44.69
1998	47.28
1999	49.96
2000	52.9
2001	54.91
2002	56.92
2003	59.03
2004	61.24
2005	63.67
2006	66.29
2007	68.92
2008	71.6
2009	74.45
2010	77.56
2011	79.37
2012	81.22
2013	83.22
2014	85.16
2015	87.12
2016	89.12