Year	Number of
1990	29.6
1991	30.86
1992	30.26
1993	30.2
1994	29.98
1995	30.5
1996	30.96
1997	31.71
1998	32.02
1999	32.37
2000	33.71
2001	34.61
2002	34.01
2003	35.07
2004	35.87
2005	37.38
2006	37.4
2007	38.71
2008	39.82
2009	40.76
2010	41.75
2011	43.16
2012	44.78
2013	45.62
2014	47.13
2015	46.97
2016	47.19