A line graph shows the number of visitors to a school garden at each hour from 9:00 to 3:00. At 9:00 there were 12 visitors, at 10:00 there were 18, at 11:00 there were 25, at 12:00 there were 22, at 1:00 there were 30, at 2:00 there were 28, and at 3:00 there were 20. Use the graph data to answer the question.
Between which two consecutive hours did the number of visitors increase by the greatest amount?
(2)