Year	Number
1975	26.70901
1984	29.01965
1985	30.46211
1987	28.37827
1988	27.3873
1989	26.59751
1993	21.50499
2000	18.45466
2002	19.34717
2003	20.30057
2004	19.1404
2007	19.77441
2010	14.28883
2011	16.81034
2013	16.17915
2014	16.49503
2015	16.42874
2016	18.10698
2017	15.49229
2018	16.69828