Year	Number of
1990	45.76
1991	45.47
1992	43.74
1993	42.2
1994	41.64
1995	40.66
1996	40.36
1997	40.28
1998	40.61
1999	40.65
2000	40.99
2001	41.51
2002	42.17
2003	43.09
2004	44.18
2005	45.31
2006	46.36
2007	47.4
2008	48.66
2009	49.76
2010	50.76
2011	51.58
2012	52.29
2013	53.01
2014	53.7
2015	54.39
2016	55.19