Westchester had the most fourth quarter residential sales since at least 1981 as inventory continued to fall sharply. There were 2,419 single-family, 2-4 family, co-op and condo sales, up 0.3% from the year ago quarter. Since the mid-2015, countywide sales have occurred at a blistering pace, as residents of New York City have increasing sought out suburban markets for greater affordability. Listing inventory continued to decline, falling 21.2% to 3,004 from the year ago quarter to the lowest fourth quarter total in 15 years…