Greater Portland’s retail real estate scene is much stronger than the nation’s as a whole.

While the U.S. average retail vacancy rate hovered around 12.6 percent in 2015, Portland and its suburbs had a rate of 3.6 percent — a figure that would have been even lower if not for the nearly 14 percent vacancy rate at the Falmouth shopping center on Route 1.

The lease rates for retail space increased 22 percent 2014 to 2015, according to an analysis presented by Karen Rich of Cardente Real Estate. Overall lease rates averaged $17.62 per square foot, with prime rates increasing 68 percent while secondary markets dropped 4 percent over the year.

The most robust retail market is in the Old Port, where leases range from $25 to $35 per square foot for space in the 1,200-1,800 square foot range. The vacancy rate for Commercial, Fore and Exchange streets is almost zero, according to Rich.

Among the top transactions recorded in 2015: The shopping center on Broadway in South Portland for $4 million; the Shops at Long Bank in Kennebunk for $6.9 million; Sebago Plaza in Windham, $1.05 million; Cook’s Lobster House in Harpswell, $1.25 million; Topsham Crossing, $1.87 million; and Ryan’s Corner House in Wells, $1.05 million.