Worldwide production of motor vehicles was 3.9 million vehicles in 1946 and…

Worldwide production of motor vehicles was 3.9 million vehicles in 1946 and 61.3 million in 1987. Of the following, which is closest to the average (arithmetic mean) annual increase, in millions, in worldwide production of motor vehicles during this period?

This problem repeats another one in the library (at most with different numbers), so it's left out of browsing.

AQuA-RAT — Algebra Question Answering with Rationales (Ling et al., DeepMind, 2017) · train #55717