Brazil Employment Structure Primary Sector Employment Structure In Brazil?

Employment Structure in Brazil? - brazil employment structure primary sector

I have some questions about the structure of employment in Brazil.

Primary sector: supply of raw materials of the earth and the sea
Secondary use of these materials to make things
Tertiary: Service

First visit, 5 years after the first Portuguese arrived there was a high percentage of primary jobs and the people in the primary sector like agriculture and mining. Why?

Second, because these factories and mines began to receive the use of machines in the primary sector fell, why did this happen?

Third, who, like factories, several computers and robots, is reduced, the secondary sector. Why?

Fourth, the richest people in the service sector is expanding, why?

Finally, a boom in tourism generated an increase in the tertiary sector, why?

I do not know about it, I really do not understand!