How about using LAST_VALUE() ?

SELECT 
    Country, 
    LAST_VALUE(Date) OVER (PARTITION BY Country ORDER BY Date 
        ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) AS Last_Date, 
    LAST_VALUE(Rate) OVER (PARTITION BY Country ORDER BY Date 
        ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) AS Last_Rate 
FROM my_tab;