This is one of several industry specific indexes I track each month.
The index increased to 101.0 in March (above 100 indicates expansion).
Unfortunately the data for this index only goes back to 2002.
From the National Restaurant Association: Restaurant Industry Outlook Gained Strength in March as Same-Store Sales, Customer Traffic Levels Continued to Improve
The National Restaurant Association’s Restaurant Performance Index (RPI) – a monthly composite index that tracks the health of and outlook for the U.S. restaurant industry – stood at 101.0 in March, up 0.3 percent from February and the third gain in the last four months. In addition, March represented the sixth time in the last seven months that the RPI stood above 100,