I have a formula which works very well in column L

=(COUNT(INDIRECT("M9"&":N"&$A$3))/$K8)

This counts my data in column M and N.
I I insert a new column before column L, the formula doesn't change to
adjust to the shift.
I would like it to read:

=(COUNT(INDIRECT("N9"&":O"&$A$3))/$K8)

The reference to column M and N is hardwired. You would think that M
and N not having a $ in front of it, that it would do so, but it
doesn"t.

How can I get the formula to automatically adjust to the addition of
another column.

Thanks!