porcentaje de total tabla

[iislas]

Bueno, yo en tu caso pondria un poco de esfuerzo y haria algo asi:

Código SQL:

SELECT 'APROBADOS' AS STATUS, 
LEFT(CAST(SUM (CASE WHEN calificacion > 5 THEN 1 ELSE 0 END) AS DECIMAL(10,2)) / CAST(COUNT(Nombre) AS DECIMAL(10,2)),4) AS '%'
FROM #alumno
UNION
SELECT 'REPROBADOS' AS STATUS,
LEFT(CAST(SUM (CASE WHEN calificacion <= 5  THEN 1 ELSE 0 END) AS DECIMAL(10,2)) / CAST(COUNT(Nombre) AS DECIMAL(10,2)),4) AS '%'
FROM #alumno