Year	Number of
1990	54.29
1991	55.38
1992	57.4
1993	59.61
1994	60.65
1995	64.4
1996	67.99
1997	71.47
1998	71.29
1999	75.93
2000	79.86
2001	79.29
2002	80.36
2003	83.92
2004	85.77
2005	87.11
2006	85.31
2007	86.02
2008	87.34
2009	89.86
2010	92.45
2011	97.52
2012	101.64
2013	107.88
2014	113.55
2015	119.69
2016	126.01