For each origin, display the origin as well as the number of unique captains who have been captains of shipments which left that port.

Relationships for shoretoshore ship no SHIP NO SHIPMENT_DATE ORIGIN grade ufacturer id ARRIVAL DATE manufacturer Manufacturer ID Name SHIPMENT ID ITEM NO QUANTITY DESTINATION DAYS Bid Preference item no type weight Relationships for shoretoshore ship no SHIP NO SHIPMENT_DATE ORIGIN grade ufacturer id ARRIVAL DATE manufacturer Manufacturer ID Name SHIPMENT ID ITEM NO QUANTITY DESTINATION DAYS Bid Preference item no type weight