Try this for creating a calculated column called Occurrences:
Occurrences =
CALCULATE (
    COUNT ( [Pais] ),
    FILTER (
        'Table',
        [Index] <= EARLIER ( 'Table'[Index] )
            && [Pais] = EARLIER ( 'Table'[Pais] )
    )
)
Index must be an incremental key in each row.
Let me know if this helps.