Dynamic query in postgresql - Rolls rates of paydays

Question

I run a query in postgresql to obtain the category of paydays in t+1 (f.e.02-28-2015) of a set of clients on a cut-off date - previous month t (f.e.01-31-2015). The result is satisfactory, however, if I wanted the rolls rate from January 2015 to January 2020, I have to run month by month, changing the month t and month t +1. They know somehow to obtain the result with a single execution of a querie, maybe a loop. Thanks in advance.

--creating the categories for month t plus 1 (Feb15)

DROP TABLE IF EXISTS rolls_rate_t_plus_1;
CREATE TEMP TABLE rolls_rate_t_plus_1 AS (SELECT 
                         a.co_contra -- Primary key
                        ,a.pe_produc -- Month of production
                        ,  (CASE
                        WHEN a.co_diamorcro <= 0 THEN '0 dpd'
                        WHEN a.co_diamorcro > 0 AND a.co_diamorcro <= 8 THEN '1-8 dpd'
                        WHEN a.co_diamorcro > 8 AND a.co_diamorcro <= 30 THEN '9-30 dpd'
                        WHEN a.co_diamorcro > 30 AND a.co_diamorcro <= 60 THEN '31-60 dpd'
                        WHEN a.co_diamorcro > 60 AND a.co_diamorcro <= 120 THEN '61-120 dpd'
                        WHEN a.co_diamorcro > 120  then '>120 dpd' 
                        ELSE 'Refinanced and canceled' END ) AS rolls_rate_t_plus_1 -- Rolls rate (paydays) category in month t plus 1  (February)       
                        FROM risk.portfolio_wfcore a
                        WHERE 
                        pe_produc= (date_trunc('month', a.pe_produc + interval '1 month' - interval '1 day')::date -1) -- Last day of the month
                        AND to_char(pe_produc,'yyyymm')='201502' -- February month (t+1)      
                        )

    
;   

--- Consolidating data from month t with month t plus one from the temporary table created previously
        
        SELECT
                         a.product -- Company products
                        ,to_char(a.pe_produc,'yyyymm') AS codmonth --Month of  production
                        ,(CASE
                        WHEN a.co_diamorcro <= 0 THEN '0 dpd'
                        WHEN a.co_diamorcro > 0 AND a.co_diamorcro <= 8 THEN '1-8 dpd'
                        WHEN a.co_diamorcro > 8 AND a.co_diamorcro <= 30 THEN '9-30 dpd'
                        WHEN a.co_diamorcro > 30 AND a.co_diamorcro <= 60 THEN '31-60 dpd'
                        WHEN a.co_diamorcro > 60 AND a.co_diamorcro <= 120 THEN '61-120 dpd'
                        WHEN a.co_diamorcro > 120  then '>120 dpd' 
                        ELSE 'Refinanced and canceled' END ) AS rolls_rate_t --Rolls rate(paydays) category in month t (January)
                       ,(CASE
                         WHEN b.rolls_rate_axes_t_mas_1 IS null THEN 'Refinanced and canceled'
                         ELSE b.rolls_rate_axes_t_mas_1 END) AS rolls_rate_t_plus_1 --Rolls rate category in month t plus 1  (February)
                       ,COUNT(a.co_contra) AS nro_credit -- nro of credits of month t (January)
                       ,SUM(a.im_salact) AS amount_credit -- amount of credits of month t (January)
FROM risk.portfolio_wfcore a
LEFT JOIN  
rolls_rate_t_plus_1  b
ON a.co_contra = b.co_contra
WHERE
a.pe_produc= (date_trunc('month', a.pe_produc + interval '1 month' - interval '1 day')::date -1)  -- Last day of the month
AND to_char(a.pe_produc,'yyyymm')='201501' -- January month (t)
GROUP BY 1,2,3,4,5,6
ORDER BY 1,2

Results:

Product	codmonth	rolls_rate_axes_t	rolls_rate_t_plus_1	nro_credit_t	amount_credit_t
Micro	201501	31-60 dpd	61-90 dpd	2	247.59
Micro	201501	61-90 dpd	Refinanced and canceled	3	2388.56
Micro	201501	61-90 dpd	31-60 dpd	26	54251.75