Counting the number of entries by lotid

[welchs101]

I have a sheet see enclosed.

What i want is two cols for the output.
Lotid and Percentage

So, for a given lotid i want to count =>
(number of No Errors)/ (number_of_errors + number_of_No_Errors)

Notice that in the file there are multiple entries for a given lotid. But what i want is as i said above

For a single lotid (so need to generate a unique list of lotids) count
(number of No Errors)/ (number_of_errors + number_of_No_Errors)