Year	Number
1971	12.03038
1972	12.77955
1973	11.77394
1974	12.06756
1975	13.61269
1976	14.43936
1977	12.48669
1978	16.70075
1979	12.04939
1980	18.88581
1982	25.82597
1983	39.96555
1984	38.80423
1985	35.08235
1986	33.22932
1990	18.19699
1993	23.3731
1995	29.77072
1996	31.76433
1999	36.15898
2000	37.52586
2001	30.753
2002	33.64818
2003	33.64833
2006	33.21599
2008	32.12563
2011	20.43101
2014	23.48523
2016	24.64362