Among the cities belonging to the country named Arroyo, calculate the percentage of increase in the population in these cities from 2010 to 2020.
DIVIDE(SUBTRACT(SUM(population_2020)), SUM(population_2010)), SUM(population_2010) as percentage where county = 'ARROYO';
SELECT CAST((SUM(T2.population_2020) - SUM(T2.population_2010)) AS REAL) * 100 / SUM(T2.population_2010) FROM country AS T1 INNER JOIN zip_data AS T2 ON T1.zip_code = T2.zip_code WHERE T2.city = 'Arroyo'