Much has been discussed here about how to build this chart, but I
haven't found anything explaining the possibility of combining it with
a second y axis. I want to graph the advertising expenditure and gross
rating points (what would be the return of investment on advertising)
on television for three diaper brands by day part. Day parts would be
represented by the different colors of which columns will consist.
There are 5 of them: day, early, prime, late and over. For each brand,
I want that two data columns. The one to the right will represent the
expenditure in $ and the one to the left the GRPs.

The thing is, there is an abysmal difference between the scale of $
and GRPs. So I want a secondary axis for each column on the right side
of each brand. This means that columns # 2, 4, and 6 will be 'ruled'
by the second y axis and the other columns of odd numbers will be
ruled by the primary y axis.

I hope you can get the idea of what I'm trying to do here. Thanks in
advance for your help.