The supplied data illustrates the information about five distinct water bodies which were coverd by ice in North America in two 20-year periods. Ice coverages were measured in percentages. overall, it is readily apparent that whereas both periods witnessed a fluctuation, 1973-92 period was the highest.
In regards to 1973-92, with a proportion of 30 being covered at Lake Erie, it was the most significant out of all. Meanwhile, Lake Ontario coverge was the least, since it was just above 5%. Moreover, Lake Huron was the second on the graph with aproximately 27%. Intaerstingly, an equal amount were coverd at Lake Superior and Lake Michigan nearly a quarter.
In sharp contrasrt to this, in comparison to the foremer period, 1993-2012 is not as covered as 1973-92 at Lake Superior,it was experienced about 21% and 15%,respectively. Moreover, an equal amount was showed at Lake Ontario about 5%. furtgermore, the second topmost was the Lake Erie,since it was reduced approximately by 2%.