SQL

select tableOne, count()/(select count() from arbol) as probabilidad from arbol where tableOne in(select distinct tableOne from arbol) group by tableOne;
select tableOne, tableTwo, count()/(select count() from arbol) as Probabilidad from arbol where tableOne in(select distinct tableOne from arbol) and tableTwo in(select distinct tableTwo from arbol) group by tableOne, tableOne order by tableOne, tableTwo;