That's largely because Americans ages 18 to 34 and families with children have cut down on dining out, and many still don't feel like the economy has improved enough to justify their prerecession restaurant spending, according to NPD's research.
Overall, many Americans have gotten used to cooking at home and actually prefer it to dining out, according to NPD. At the same time, the restaurant industry has been facing more competition from improved heat-and-eat and premade meal options from grocery stores, Riggs said.
In the past six years, families with kids made 1 billion fewer visits to U.S. restaurants than in the previous six years, and adult-only parties made 306 million fewer visits during that period, according to a recent NPD report.
In order to lure families back, restaurants could stand to improve their kids menus to cater to more adventurous young eaters, according to Riggs. Restaurants might consider having a "'tweens'" menu that offers more variety than a traditional kids' menu, but smaller portions, Riggs suggests.
Restaurants should also make sure that their wait staff is friendly to kids and offer families fast service with little wait time, Riggs said.