(Adds details on 2014 deliveries, background)
SEATTLE, Feb 12 (Reuters) - Airbus Group forecast on Thursday that 36 percent of its A320 aircraft family deliveries this year will be the A321 jetliner, up from 31 percent in 2014.
"By end of this year, 36 percent of deliveries will be A321, and it will be an even bigger proportion as we move forward," Simon Pickup, strategic marketing director at Airbus Americas, said at an industry conference near Seattle.
Airbus delivered 150 of the 185-seat A321 passenger aircraft in 2014, or 31 percent of a total of 490 single-aisle A320-family airplanes, which compete with Boeing's 737 family.
The proportion of A321s making up total single-aisle deliveries from the European planemaker has risen 10 percentage points over the past five years.
Boeing has said it sees the single-aisle market centered around planes of 160 seats but last year announced plans for a 200-seat model of its 737, the rival to Airbus' A320 family.
South Korea's Asiana Airlines this week announced a preliminary deal to buy 25 of a planned revamped version of the A321. (Reporting by Alwyn Scott and Tim Hepher; Editing by Jonathan Oatis)