If the luxury segment of the cruise industry accounted for 2.35% of the industry's capacity in 2013, how much will that number have grown by 2020?
It's a trick question. The luxury segment will shrink to 1.78% of the industry by 2020, according to Regent Seven Seas Cruises president Jason Montague, even though every luxury line will have added one or more ships over that period.
Regent's contribution to the total will be the 750-passenger Seven Seas Explorer, the largest ship ever to sail for Regent.
Other lines that Montague counts in the luxury column include Crystal Cruises, Hapag-Lloyd Cruises, Ponant, Seabourn and Silversea Cruises.
All have new ships or plan to add them. So how can the luxury segment be shrinking?
Montague says the answer lies in the size of the ships that other segments of the industry are building. The very biggest lines are now taking ships with capacity for 4,000-plus passengers. The premium lines, from which luxury lines draw some of their prospective customers, are also building bigger ships, from 2,500 to 3,500 passengers.
So it's not that luxury isn't growing, it's that in absolute terms the others are growing faster.
That all bodes well for the luxury players, Montague argues. The more people that cruise, the more there are in a position to move up the ladder to luxury as they age or get tired of the ships they're on.
Frank Del Rio, Montague's boss and chairman of Norwegian Cruise Line Holdings, throws out another more practical reason why the luxury segment doesn't keep pace. There are only so many shipyards, and the main players make more money building big ships than small ones.
That's one reason why when Crystal Cruises wanted to add three ships in three years, its parent company bought a shipyard to insure the work got done.
Regent's pace is more typical. It just launched the Seven Seas Explorer and won't take a second version of it for another four years.
By then there will be more wealthy people than ever, Del Rio says. "The world is getting wealthier, and not just North America," he said.
That should provide more passengers for the luxury lines' new ships, even if they charge $10,000 a night like Regent does for the top suite on the Seven Seas Explorer.