Answer:
3 years
Step-by-step explanation:
Even there was a dry year in 1979, the area received almost the normal amount of rain in 1980.
In 1981 however, the year was quite dry, with rainfalls in drop of almost 20%, that began one of the most important drought in the history of Brazil.
In 1982, rainfalls were down by 30% and it got even worse.
In 1983, the rainfalls were down by about 35%, essentially destroying all the agriculture system that had been severely damaged by the two previous years.
In 1984, rain came back a bit higher than its traditional levels, and in 1985, the area was flooded by rain surpassing the average by 60%!