In a reversal of the previous quarter sales pattern, the Palm Beach high-end market saw a significant increase in activity, concentrated in the North End to close out 2017. The average size of a single-family sale surged 80.9% to 6,021 square feet from the year-ago quarter. The luxury market, which was comprised of the top 10% of all sales and was solely single-family sales, surged 87.6% to 9,429 square feet over the same period. Conversely, the condo average sales size fell 7.2% to 1,669…