Query Espinoza Francisco Ing del conocimiento

select tabal, count (*)/ (select count(*) from arbol) as probabilidad from arbol where tabal in (select distinc tabal from arbol) group by tabal;
select tabal, tabal2, count(*)/(select count(*) from arbol) as Probabilidad from arbol where tabal in (select distinct tabal from arbol) and tabal2 in(select distinct tabal2 from arbol) group by tabal2, tabal order by tabal, tabal2;