If the length of our lives is a good measure of our wellbeing, the United States is in some trouble. The average life expectancy for an American born in 2021 was just shy of 76 years and 5 months — more than half a year shorter than it was in 2020, according to a new government report. It was the lowest such figure since 1996 and follows roughly a decade of stagnation in adding years to our…