RMontgomery

1/ Insert 10 rows ABOVE all your data.
2/ enter the following ARRAY formula (ctrl-shift-enter) into A1
{=SUM(OFFSET(A$11,0,0,COUNT(A$11:A$65000),1)*(CEILING(RANK(OFFSET(A$11,0,0,COUNT(A$11:A$65000),1),OFFSET(A$11,0,0,COUNT(A$11:A$65000),1))/COUNT(A$11:A$65000)*10,1)=ROW()))/SUM(1*(CEILING(RANK(OFFSET(A$11,0,0,COUNT(A$11:A$65000),1),OFFSET(A$11,0,0,COUNT(A$11:A$65000),1))/COUNT(A$11:A$65000)*10,1)=ROW()))}
3/ Fill down to A10, then fill right
A1:A10 will give you decile averages for col A, B1:B10 for col B…
andd soo on and sooo on