user: Question: What is the highest stage number for a year later than 1948, leader at the summit was Group, and finish was Bagnères-de-Bigorre?
Columns: ['Year', 'Stage', 'Start', 'Finish', 'Leader at the summit']
Types: ['real', 'real', 'text', 'text', 'text']
Sample row: [2012.0, 17.0, 'Bagnères-de-Luchon', 'Peyragudes', 'Thomas Voeckler ( FRA )']
SQL:

assistant: SELECT MAX("Stage") FROM "Table" WHERE "Year" > 1948.0 AND "Leader at the summit" = 'Group' AND "Finish" = 'Bagnères-de-Bigorre';