A recent report from Technavio, a global technology research and advisory company, revealed that the global hot tub market’s compounded annual growth rate is expected to increase 4.9% from 2017 to 2021.

The report takes into account above-ground hot tubs as well as portable tubs and inground tubs, and the projected growth rate is based on a number of factors, including increasing average dual-household income levels, and economic recovery.

Nancy Nelson, owner of Nelson’s HomeTowne Recreation in Janesville, Wisc., believes that the 4.9% increase isn’t quite accurate.

“I think it’s low,” she says. Her hot tub category is up by about 20% over last year, and she expects the category to keep doing well. She attributes the sales increase to her customers’ disposable income levels, as well as local millennials who are starting to buy homes and like to invite family and friends over to entertain.

However, she does recognize that a retailer’s hot tub sales growth will depend largely on the economic prosperity of each location.