I’m reading the book A History of Brazil by E. Bradford Burns and ran across the following paragraph:

The increasing income from the rubber industry made possible comfortable budgets for the governments of Amazonas and Pará. The principal interest both of those governments displayed in the industry was to levy taxes. A 20 or 25 percent export tax on each kilo of rubber enriched the treasuries. For Amazonas, the state budget in 1910 of 15.561:000$000 was exceeded by an income of 18.069:162$372. Rubber provided 82.11 percent of that income. In the previous year it had furnished 79.04 percent and in 1911 it would provide 77.50 percent.

What is the meaning of 15.561:000$000 and of 18.069:162$372?  They appear to be referring to money, but what is the currency?  Why is it written that way?  The Author provides no clues!  Any ideas would be appreciated.

Be well.  CRS