Year	Number of
1990	30.23
1991	31.94
1992	34.59
1993	37.41
1994	39.9
1995	42.25
1996	44.64
1997	45.2
1998	46.49
1999	48.48
2000	50.97
2001	55.24
2002	59.28
2003	63.93
2004	68.76
2005	72.63
2006	75.67
2007	79.05
2008	82.72
2009	87.33
2010	92.66
2011	97.65
2012	103.91
2013	109.62
2014	114.97
2015	119.9
2016	124.41