Year	Number of
1990	62.18
1991	63.78
1992	65.71
1993	67.79
1994	69.87
1995	72.2
1996	74.27
1997	76.54
1998	78.98
1999	80.94
2000	83.16
2001	85.49
2002	87.96
2003	90.97
2004	94.07
2005	97.36
2006	100.4
2007	103.6
2008	107.36
2009	111.35
2010	115.65
2011	120.62
2012	125.88
2013	131.35
2014	137.31
2015	143.81
2016	150.54