Year	Number of
1990	80.07
1991	79.42
1992	78.97
1993	79.2
1994	80.69
1995	83.82
1996	88.25
1997	94.77
1998	102.39
1999	109.85
2000	116.56
2001	122.28
2002	127.11
2003	131.57
2004	136.63
2005	143.04
2006	150.21
2007	158.71
2008	168.42
2009	178.65
2010	189.17
2011	196.76
2012	204.31
2013	211.9
2014	219.94
2015	228.62
2016	237.59