The US housing market has softened a bit after years of soaring prices and frantic bidding wars, but there’s little reprieve for buyers trying to crack into the market. First-time buyers made up the smallest share of sales on record last year, at 26%, even as home values started to cool, according to the National Association of Realtors. And rising borrowing costs and still-high prices have pushed housing to the most unaffordable levels in records going back almost four decades.