Why does the percentage of questions for which a user has accepted an answer not appear anymore? Is there a way to see this information?
This was a decision made by the good folks at Stack Exchange. See the question, answers, and comments there for the whys and wherefores.
The Stack Exchange API still returns a value for accept_rate for a user query.
For example: http://api.stackexchange.com/2.1/users/883?order=desc&sort=reputation&site=judaism&filter=!nTBZKAKmnK returns a key:value pair of