Divide Rows by Rows

Hello,

I have a table Table 1

COL1 ----------     COL2

Local ----------  10

Global ---------- 20

Local ----------15

Local ---------- 30

Global ----------15

Global ----------10

What I'm trying to do is create a measure, where SUM COL2 where COL1 is Local gets  divided by SUM of CLO2 Where COL1 is Global

So basically SUM(Local.COL2) / SUM(Glocal.COL2)

Apprecite your help.