Year	Number of
1990	60.06
1991	62.03
1992	65.6
1993	69.37
1994	73.45
1995	77.07
1996	80.02
1997	82.83
1998	85.97
1999	87.36
2000	89.03
2001	90.64
2002	94.01
2003	97.47
2004	101.43
2005	104.6
2006	106.59
2007	109.22
2008	112.07
2009	116.23
2010	121.94
2011	126.4
2012	132.2
2013	137.77
2014	143.44
2015	148.88
2016	154.23