What are the names of players who won in both 2013 and 2016?
SELECT winner_name FROM matches WHERE YEAR  =  2013 INTERSECT SELECT winner_name FROM matches WHERE YEAR  =  2016
SELECT winner_name FROM matches WHERE YEAR  =  2013 INTERSECT SELECT winner_name FROM matches WHERE YEAR  =  2016
[{'winner_name': 'Angelique Kerber'}, {'winner_name': 'Petra Kvitova'}, {'winner_name': 'Sara Errani'}, {'winner_name': 'Serena Williams'}, {'winner_name': 'Victoria Azarenka'}]