Question: When turquoise is the map colour how many avg. trips per mile (×1000)  are there?
Schema: create table table_17839_1 (avg_trips_per_mile__ varchar, map_colour varchar, PRIMARY KEY (avg_trips_per_mile__))
SQL: select count(avg_trips_per_mile__) as ×1000_ from table_17839_1 where map_colour = "turquoise"