Year	Number
1971	6.01552
1972	6.10665
1974	7.84244
1976	8.23119
1991	8.9895
1992	9.9783
1993	11.28307
1994	12.19305
2012	29.49606
2013	26.94957
2014	29.61281
2015	28.92712
2016	27.26886
2018	26.51922