Percentage Increase in Internet Usage

The following line graph illustrates the monthly internet usage (in gigabytes) of a family over the first six months of the year. The months are represented on the horizontal axis, while the vertical axis shows the amount of data used in gigabytes.

In January, the family used 60 GB, which increased by 20 GB in February. March saw a decrease to 70 GB, April remained steady, but in May, usage spiked to 110 GB. Finally, June saw a drop back to 90 GB.

Based on the data presented in the graph, which month had the greatest percentage increase in internet usage compared to the previous month?