Year	Number
1971	15.23585
1972	19.9
1975	17.29787
1976	21.25301
1977	21.68675
1978	21.15
1997	17.47778
1999	18.40404
2001	17.69106
2002	17.95798
2003	15.21008
2014	9.28772
2018	17.69231