Year	Number of
1990	93.7
1991	97.06
1992	97.73
1993	101.16
1994	104.92
1995	106.5
1996	107.83
1997	110.07
1998	112.42
1999	117.33
2000	124.54
2001	135.85
2002	146.73
2003	157.51
2004	173.81
2005	187.66
2006	195.18
2007	212.81
2008	230.48
2009	251.06
2010	268.29
2011	275.45
2012	279.23
2013	283.43
2014	282.97
2015	281.69
2016	282.92