The National Restaurant Association's Restaurant Performance Index stood at 101.6 in April, up 0.9 percent from March. The National Restaurant Association attributes the moderate gain to stronger same-store sales and customer traffic levels. Any reading that exceeds 100 indicates expansion among the index of restaurant industry-related performance indicators.

The Current Situation Index stood at 102.1 in April — up 1.9 percent from a level of 100.2 in March.

Fifty-eight percent of restaurant operators reported a same-store sales gain between April 2015 and April 2016, up from 46 percent who reported higher sales in March. In addition, 52 percent of operators reported an increase in customer traffic levels between April 2015 and April 2016.

Sixty-four percent said they made a capital expenditure for equipment, expansion or remodeling during the last three months. Similarly, 58 percent say they plan to make a capital expenditure in the next six months.

The Expectations Index stood at 101.0 in April — down 0.2 percent from March. Operators' six-month outlook for sales softened for the second month in a row and their opinions are mixed about the direction of the overall economy, according to the study.