Year	Number of
1990	37.13
1991	38.61
1992	40.1
1993	41.64
1994	43.27
1995	45.03
1996	46.59
1997	48.28
1998	50.1
1999	52.06
2000	54.18
2001	56.24
2002	58.43
2003	60.78
2004	63.29
2005	66.01
2006	68.48
2007	71.07
2008	73.88
2009	76.89
2010	80.15
2011	82.74
2012	85.51
2013	88.42
2014	91.51
2015	94.82
2016	98.43