Year	Number of
1990	28.99
1991	29.61
1992	30.35
1993	31.3
1994	32.2
1995	32.77
1996	32.46
1997	33.16
1998	33.07
1999	32.68
2000	32.81
2001	33.13
2002	33.86
2003	34.07
2004	34.38
2005	34.73
2006	34.92
2007	35.38
2008	35.31
2009	35.38
2010	36
2011	37.35
2012	38.38
2013	40.28
2014	42.07
2015	43.96
2016	44.96