How to get percentage after grouping?

I have a table like this: person_id food data 1 bread xxx 1 bread xxx 1 fruite xxx 2 bread xxx 2 fruite xxx food can have only three values (bread, fruits), I want to get the percentage of bread each person has eaten, and there percentage of fruits each person has eaten. I tried to do: select count(*) from table group by person_id, food and that gives me: player_id, food, number but how can I continue from now? I am on hadoop