US softwood lumber prices extended their six-day losing streak on Monday after homebuilder sentiment fell for the 12th month in a row.    US lumber futures dropped as much as 4% to $370.40 per thousand board feet, representing a fresh low for 2022 and its lowest level since June 2020.    The essential building commodity is now down 68% year-to-date and is off 79% from its record high reached in May 2021, when strong demand for homes was compounded by supply chain issues.    The weakness in ...