Year	Number of
1990	81.93
1991	83.99
1992	86.39
1993	88.41
1994	90.93
1995	93.99
1996	97.39
1997	101.12
1998	105.46
1999	109.76
2000	114.11
2001	118.03
2002	122.08
2003	127.33
2004	132.71
2005	138.39
2006	141.97
2007	145.53
2008	149.45
2009	153.66
2010	158.43
2011	162.86
2012	167.86
2013	173.1
2014	178.4
2015	183.71
2016	189.81