USD Inflation Facts From The Last 40 Years 1978-2018poias (46) in food • 7 years ago $50 in 1978 is equivalent in purchasing power to $190.94 in 2018. The average yearly inflation rate of the USD from 1978 - 2018 is 3.14% The current inflation rate in 2018 is 1.72% $50 today will be equivalent to $50.86 next year. food economics trivia usd math