Marketshare DAX

Anonymous Can't be sure without sample data but can you do this?

Measure =
  VAR __Country = SUM('Table1'[Country])
  VAR __Clients = SUM('Table2'[My clients])
  VAR __Result = DIVIDE( __Clients, __Country, 0 )
RETURN
  __Result

Otherwise, Sorry, having trouble following, can you post sample data as text and expected output?
Not really enough information to go on, please first check if your issue is a common issue listed here: https://community.powerbi.com/t5/Community-Blog/Before-You-Post-Read-This/ba-p/1116882

Also, please see this post regarding How to Get Your Question Answered Quickly: https://community.powerbi.com/t5/Community-Blog/How-to-Get-Your-Question-Answered-Quickly/ba-p/38490

The most important parts are:
1. Sample data as text, use the table tool in the editing bar
2. Expected output from sample data
3. Explanation in words of how to get from 1. to 2.