With reference to the figure below, assume that the average annual deposition of sulfur in the watershed of Big Moose Lake between 1880 and 1920 was 0.8 g S m^-2, and from 1921 to 1950 it was 2.5 g S m^-2. Calculate the cumulative acid equivalents per square meter that were deposited in the watershed over the entire period 1880-1950.