Year	Number
1986	10.09165
1987	10.67753
1988	10.73553
1989	11.49096
1990	12.63866
1991	10.98149
1992	14.22636
1993	13.95455
1994	15.29488
1995	15.09966
1996	15.11298
1997	16.21565
1998	15.95574
1999	16.21729
2000	16.97175
2001	17.00998
2002	18.7944
2003	19.89024
2009	20.17841
2017	9.88393
2018	9.68869