Year	Number
1981	23.95614
1992	26.14061
1994	24.64743
1995	23.76422
1996	23.03645
1997	23.14209
1998	23.03324
2000	28.12209
2001	27.95442
2002	27.8225
2003	28.16087
2004	28.1581
2008	26.03275
2011	30.75971
2012	27.99728