instruction: Comentarios que empiezan con @.
response: WITH CantPorMes AS (SELECT DATEADD(month, DATEDIFF(month, 0, CreationDate), 0) AS Mes, SUM(CASE WHEN Text LIKE '@%' THEN 1 ELSE 0 END) AS Arrobados, COUNT(*) AS Total FROM Comments GROUP BY DATEADD(month, DATEDIFF(month, 0, CreationDate), 0)) SELECT Mes, ROUND(100.0 * Arrobados / Total, 2) AS "porcentaje_arrobados" FROM CantPorMes WHERE Mes >= '2019-01-01' ORDER BY Mes