### # Running value divided by average i.e. x/mean(x) 
### using JuliaDB
### t = table([1,2,3,4,5], [1,1,1,2,2], names=[:t,:x])
### 
### @time t2 = pushcol(t, :z, 
### 		map(mr->mr.x/mean(select(filter(row->row.t <= mrg.t, t), :x) ), 
### 		    t) 
### 	);
### 
