Boston condo sales jumped to their highest first-quarter total in 16 years, according to a recent Douglas Elliman Downtown Boston market report.

Sales jumped 18% year over year in the first quarter to 637, the highest first-quarter total since 2006. The average square foot of a sale declined for the fourth straight quarter to 1,132 square feet, 9.1% below the same period last year. 

The median sales price fell 16.6% below last year’s record of $1.01 million, the fourth consecutive quarterly decline. Listing inventory rose 44.9% year over year but fell 46.7% from the third quarter of 2020 in the wake of last spring’s COVID-induced lockdown. 

The report also found condominiums are staying on the market longer — an average of 83 days — four days more than the same period last year. 

Townhouse sales trended similarly, surging from last year during the first quarter and rising for the first time in five quarters. There was a 3.4% year over year drop in sales, while the average square foot of a sale was 18.6% below the year-ago period and down for the fourth straight quarter. 

The median sales price of a townhouse fell 2.3% to just over $1.5 million for the fourth consecutive quarterly decline. Listing inventory increased 32.3% year over year but was down 51.2% from last summer’s spike.