Transact SQL :: Percentage In Simple Query

I totally forgot how can I make a percentage. Look at the code below:

create table #acca (name varchar(10), tipo varchar(10), lett int)
insert into #acca values ('Italy','Europe',15), ('France','Europe',10), ('Colombia','America',15), ('Cile','America',75)
select * from #acca

/*Query Number 1 */
select name, tipo, lett, sum(lett) over (partition by tipo) as TotCon,
sum(lett) as Total
from #acca group by name,tipo,lett;

/*Query Number 2*/
with cte as (
select name, tipo, lett, sum(lett) over (partition by tipo) as TotCon,
sum(lett) as Total
from #acca group by name,tipo,lett)
select name, tipo, lett/totcon from cte
 
Question query number 1: how can I retrieve the absolute total? Sum(lett) over what?
Question query number 2: why lett / totcon retrieves 0?
Question plus: is there a way to retrieve the percentage without using the cte?