Final answer:
David should use graphs such as pie charts, bar graphs, or line graphs to visually represent the percentage increase in sales over the last five years in his company.
Step-by-step explanation:
David should use graphs to present the percentage increase in sales in his company over the last five years. While tables organize data well, graphs like pie charts and bar graphs can visually convey changes and trends in the data more effectively. Specifically, a pie chart can illustrate parts of a whole, making it clear how each year's sales contributes to the total. Alternatively, a line graph is excellent for displaying the trend of sales over time, highlighting the percentage increase per year.
A bar graph could also be used to compare the sales figures side by side for each of the five years. David should ensure that the graphs chosen are clear and legible, with distinguishable colors for different data points and a clearly labeled scale.