I am using mysql workbench 8.0

I am teaching myself SQL and am currently starting on some guided projects with a LOT of googling. Right now I am working with this data:

Here’s the relevant section I am working with:

on and on and on. What I currently have is the following:

What I want is another column next to the cust_num column that has the percentage of total customers per branch per type, so basically:

These are the 2 most promising solutions I’ve tried

1. I actually used this solution with this code:

with rawdata as 
(SELECT branch, `Customer Type`, count(`Customer Type`) as type_count
from sales
group by 1)
groupeddata as
(SELECT `Customer Type`, count(`Customer Type`) as totalcust
from sales
Group by 1
)
SELECT r.branch, r.`Customer Type`, r.type_count, r.type_count/g.totalcust * 100.0 as percentage
from rawdata r
JOIN groupeddata g on r.`customer type` = g.`customer type`
order by 1

That gave me a percentage of I think the percentage of the customer type, but I want the percentage of the customer type within a branch. I’ve also tried putting in branch into the groupeddata and also put it in the JOIN part of the code but then the percentages all changed to 100%

Just in case I was completely overthinking it, I tried

select branch, `customer type`, count(`customer type`) as type_count,
(SELECT count(`customer type`)/sum(`Customer type`)) As percentage from sales
group by 1,2
order by 1

returns null. I know that the problem is the sum(customer type) because it’s not a number, but when I try to switch it to type_count/count(customer type) it gives me an error that type_count doesn’t exist