The median estimate from economists surveyed by the National Association for Business Economics calls for the American economy to grow 2.2 percent in 2017, up from a forecast 1.6 percent this year and unchanged from the previous survey in September. [...] the business economists say Americans need to get used to slow growth: 80 percent of those surveyed believe the potential growth rate of the American economy will remain at 2.5 percent or lower over the next five years. Two-fifths of the economists say increased spending on roads, bridges and other infrastructure projects would be the best way to boost economic growth over the next four years; 36 percent chose tax reform, which usually includes reducing the high official U.S.