Year	Number
1971	32.76109
1972	34.35157
1973	34.6412
1974	43.50298
1975	49.64053
1976	41.86005
1977	46.23432
1978	46.61157
1979	65.56436
1988	22.95897
1989	23.16133
1991	24.03219
1993	27.22762
1994	27.96994
1995	29.55942
2000	24.27353
2002	24.80104
2003	22.90848
2004	21.40568
2005	20.69556
2006	19.65949
2007	18.63931
2012	26.3367
2013	28.19049
2014	27.52765
2015	26.83345
2016	26.31507
2017	25.40425