WASHINGTON—New orders for key U.S.-made capital goods increased for an eighth straight month in December, pointing to solid growth in business spending on equipment in the fourth quarter and likely helping to underpin the economic recovery. Orders for non-defense capital goods excluding aircraft, a closely watched proxy for business spending plans, rose 0.6 percent last month, the Commerce Department said on Wednesday. These so-called core capital goods orders advanced 1.0 percent in November. Last month’s increase was in line with economists’ expectations. Core capital goods orders surged 1.8 percent year-on-year in December. Demand has shifted away from services like travel and hospitality towards goods like motor vehicles, electronics, and medical equipment during the COVID-19 pandemic. That has contributed to boosting production at factories, though output remains about 2.6 percent below its pre-pandemic level. Manufacturing, which accounts for 11.9 percent of the economy, is also being supported by businesses rebuilding depleted …