What underlying factor causes the real GDP to be above the nominal GDP in early years of time series and below in the later years?

Question

Quizplus · Accepted Answer

Increasing price levels over time cause nominal GDP to rise faster than real GDP, leading to real GDP being below nominal GDP in later years. Real GDP is adjusted for inflation, while nominal GDP is not, so as prices increase, the gap between nominal and real GDP widens.

What Underlying Factor Causes the Real GDP to Be Above