The x-axis is the 'Years' going from 1980 to 2004 in increments of 4. The left y-axis is the 'Total number of polio cases' going from 0 to 60,000 in increments of 10,000 and right y-axis shows 'Percentage of Population Vaccinated' going from 0 to 90 in increments of 10. The number of polio cases has decreased significantly from 50,000 in 1980 to nearly 0 in 2004. The percentage of people vaccinated has increased from nearly 30 percent in 1980 to about 85 percent in 2004.