Analyze the chart below and answer the question that follows. A 5-column table with 2 rows. Column 1 has entries Literacy rate, percent of people living on less than 1 dollar a day. Column 2 is labeled Mali with entries 26 percent, 51 percent. Column 3 is labeled Zimbabwe with entries 91 percent, 56 percent. Column 4 is labeled Ghana with entries 65 percent, 30 percent. Column 5 is labeled Democratic Republic of the Congo with entries 67 percent, 59 percent.
Data courtesy of the World Health Organization and Goal USA

According to the data displayed on the chart above, what conclusions can be drawn about the relationship between income and literacy in sub-Saharan Africa?