A Poli 30 Student (Data Dan) investigates the relationship between Democracy and Life Expectancy. They collect data about 156 countries all over the world. They analyze two variables: Life Expectancy is the average expected years of life at birth and DemocracyScore is a dummy variable coded "1" for democracies and "0" for non democracies. One of their colleagues says, "No way! There's a confounding variable. Richer countries tend to be democracies, and richer countries have higher life expectancy. So it's income, not democracy, that matters!" To test this, Data Dan re-runs the data, now including another variable, Average Income, to account for how rich countries are. Average Income is Per Capita Income in Dollars. Interpret the slope for Average Income from Regression #2, the regression of Life Expectancy on Democracy Score and Average Income