Year	Number of
1990	73.2
1991	76.53
1992	79.89
1993	83.33
1994	87.03
1995	91.04
1996	94.77
1997	98.92
1998	103.57
1999	108.59
2000	114.04
2001	120.6
2002	127.62
2003	135.13
2004	143.11
2005	151.7
2006	159.05
2007	166.79
2008	175.15
2009	183.99
2010	193.27
2011	200.86
2012	208.95
2013	217.48
2014	226.04
2015	234.63
2016	243.62