Restore percentage seen that was dropped from lists.

At one time, lists of titles would reveal the percentage of the titles in the list the user had marked as having seen (based on whether a rating had been assigned to any of the titles.) It appears to be gone now. It was a useful feature, very similar to the "How Many Episodes Of 'XXX' Have You Seen?" for TV Series. (Example 'Star Trek' https://www.imdb.com/seen/tt0708455/?ref_=bd_tv )

I created the following just so I and others could track progress for which of the Three Stooges' shorts they have seen but now, without the "Percentage Seen" value, the listing doesn't have that fun feature.

https://www.imdb.com/list/ls031724575/