Year	Number of
1990	30.91
1991	31.52
1992	32.18
1993	32.79
1994	33.58
1995	34.43
1996	35.13
1997	35.94
1998	36.87
1999	38.05
2000	39.24
2001	40.38
2002	41.86
2003	43.68
2004	45.51
2005	46.93
2006	49.32
2007	51.89
2008	54.56
2009	59.09
2010	62.42
2011	64.98
2012	68.56
2013	73.39
2014	78.61
2015	83.96
2016	88.55