Output count percentage in 2 decimal places I have the following sql query code and I can not get to execute the desired output. 

SELECT Deal_type, Price_type, 
cast(sum(Deal_type)/count(Deal_type)*1.0 as decimal(12,2)) as results
FROM [dbo].[all] 
WHERE Deal_type in ('RMBS','abs', 'cmbs', 'clo', 'cdo') 
GROUP BY Deal_type,Price_type order by Deal_type


I am trying to display the percentage values in decimal and currently its displaying the error message - 


  Operand data type nvarchar is invalid for sum operator.


Any help with the above query would be very much appreciated.
Are you looking for something like this..

SELECT 
    Deal_type, 
    Price_type, 
    count(isnull(Deal_type, 'x')) * 100 / (
        SELECT count(1) 
        FROM users 
        WHERE Deal_type in ('RMBS','abs', 'cmbs', 'clo', 'cdo') 
    ) as results
FROM [dbo].[all] 
WHERE Deal_type in ('RMBS','abs', 'cmbs', 'clo', 'cdo') 
GROUP BY Deal_type,Price_type 
ORDER BY Deal_type