Table: navy_ships_stats
Columns: nato_member
aircraft_carriers
battleships
cruisers
escorts
submarines
torpedo_boat_squadrons
s_motor_ship_s_naval_trawler
grand_total

Question: How many ships for the nation with grand total of 20?
SQL: SELECT "s_motor_ship_s_naval_trawler" FROM navy_ships_stats WHERE "grand_total" = 20

Question: How many escorts does the nation with 6 cruisers have?
SQL: SELECT "escorts" FROM navy_ships_stats WHERE "cruisers" = '6'