Year	Number of
1990	68.47
1991	70.85
1992	73.32
1993	75.79
1994	78.3
1995	80.96
1996	83.61
1997	86.05
1998	88.53
1999	90.83
2000	92.85
2001	95.74
2002	99.06
2003	101.82
2004	105.23
2005	108.8
2006	112.42
2007	116.27
2008	120.33
2009	124.59
2010	129.11
2011	133.84
2012	138.77
2013	143.53
2014	148.94
2015	154.47
2016	160.24