Year	Number
1978	4.33636
1985	16.59412
1987	21.512
1988	20.17537
1989	21.75281
1990	21.51852
1991	20.07143
1992	23.4
1993	28.19925
1994	28.42593
1995	28.7963
1996	31.46667
1997	38.27801
1999	34.02
2001	30.00997
2003	25.32861
2004	28.07251
2005	24.60112
2006	28.77337
2008	33.34444
2009	33.83514
2010	38.35356
2011	41.84197
2012	44.80702
2013	42.95313