Year	Number
1974	12.08889
1975	15.50396
1976	11.09453
1977	12.82727
1978	13.82172
1983	12.70856
1989	21.75756
1991	22.38355
2001	22.46411
2005	27.15291
2006	23.8663
2007	25.65364
2013	60.00969