Question: On which Portuguese island has the largest European airline by scheduled passengers flown had a base since 2015?

Ryanair Ltd. (/raɪə'ner/) is an Irish low-cost airline founded in 1984, headquartered in Swords, Dublin, Ireland, with its primary operational bases at Dublin and London Stansted airports.  In 2016, Ryanair was the largest European airline by scheduled passengers flown, and carried more international passengers than any other airline.  (, , NASDAQ: RYAAY ) <SEP> Blue Air is an airline headquartered in Bucharest, with its main hubs at Henri Coandă International Airport and Turin Airport.  Since 2016, it has become the largest Romanian airline by scheduled passengers flown.  In 2016, Blue Air carried 3.6 million passengers, a significant increase over the 2 million passengers flown the previous year.  As of May 2017, Blue Air flies to 70 destinations.  Despite operating as a low-cost airline, Blue Air started introducing free sandwiches and drinks on-board shorter flights, and a full hot meal, snacks, hot/cold and alcoholic beverages on longer flights.  This is considered unheard of in the low-cost sector, particularly as traditionally 'full service' carriers such as British Airways controversially removed free meals, snacks and drinks in 2017, and is considered key to Blue Air's continued success. <SEP>  Situated 2 km west of the city centre of Ponta Delgada, it is the primary (and busiest) airport in the Azores, as well as the fifth largest infrastructure managed by ANA Aeroportos de Portugal; with the construction of the terminal in 1995, by 2005 the airport served a total of 873,500 passengers.  It has scheduled domestic flights to all islands of the Azores, plus Madeira and the mainland, namely (Lisbon, Porto and Faro).  João Paulo II Airport also accommodates international flights to and from Europe and North America.  The airport is the major hub for the SATA Group of airlines, which includes both inter-island SATA Air Açores and international Azores Airlines, and since April 2015 as a base for Ryanair. João Paulo II Airport (IATA: PDL, ICAO: LPPD) , named after Pope John Paul II, is an international airport located on the island of São Miguel, in the Portuguese archipelago of the Azores. <SEP> Bay of Angra (Portuguese: "Baía de Angra" ) is a natural bay within the coastal extent of the municipality of Angra do Heroísmo, on the Portuguese island of Terceira in the archipelago of the Azores.  Within an average depth of 40 m , the bay has been of historical importance to the island; since the 15th century, it was a port-of-call for returning merchant shipping from the East Indies and Brazil, laden with gold, silver, porcelain, spices, rare woods, and other goods.  These ships would anchor in the Bay of Angra until supported by armed escorts, which would accompany the ships on the rest of their voyage to Portugal.  The Bay at Angra provided shelter from northern and northwestern winds; only storms originating to the south or southeast, posed a threat.  Nonetheless, the Bay is the final resting-place of several ships affected by the adverse winds: local archives and a rich oral tradition supports the foundering of many ships against the leeward shore.