The year 1850 is used because historians and economists prefer round numbers. The source says: "As exportações brasileiras triplicavam as da Argentina em 1850, segundo cálculos de Bulmer Thomas... Em termos internacionais mais amplos, o valor absoluto das exportações brasileiras era o mais elevado da América Latina, enquanto o da Argentina ocupava o quarto lugar." In English: The Brazilian exports were the triple of Argentina's in 1850, according to calculations by Bulmer Thomas... In more ample international terms, the absolute value of Brazilian exports were the highest in Latin America, while Argentine held the fourth place." The book was written by the Brazilian historian Boris Fausto and the Argentine historian Fernando J. Devoto. It's a comparative history of Brazil and Argentina from 1850 until 2002. I used the edition in Portuguese. There is an edition in Spanish ("Argentina y Brasil, 1850-2000: un Ensayo de Historia Comparada") published by Sudamericana Buenos Aires. Of course, if anyone has data regarding other years I would be glad to see them. They would be useful in Economy of the Empire of Brazil.