Virginia retail sales rose at a marginally higher rate last year than the national average, a University of Virginia report said yesterday.

The report prepared by the university's economic research arm, the Tayloe Murphy Institute, said retail sales in the state totaled $16.8 billion in 1978, up 12 percent over $14.7 billion in sales in 1977.

During that period, retail sales climbed 11 percent nationally, continuing a trend found in every year, except 1975, said Eleanor M. May, the institute's business studies research director, began analyzing the figures in 1972.

She based her report on state retail sales tax revenues, including services such as hotels, motels and restaurants. It excluded taxes on automobiles and gasoline, which are special taxes and not general retail taxes.

The report, for the first time, related sales to personal income.

"Comparatively high sales per capita were found in the two types of areas," May said. "In the larger metropolitan areas, northern Viginia, Richmond, Norfolk and Newport News, higher sales per capita occur either because people residing there have a more costly lifestyle or because people from outside the metropolitan area shop there.

"A few other areas, such as the Shenandoah Valley, also stand out, with relatively low per capita personal income, high per capita taxable sales, and low per capita sales."