Calculating the Average from a Line Graph

In a school survey, students were asked how many hours they spend on various activities during the weekend. The data was represented in the following line graph:

Weekend Activities

Activity          | Hours Spent
-----------------|-------------
Sports           | 4
Reading          | 3
Screen Time     | 5
Family Time     | 2
Hobbies         | 3

From this graph, what is the average number of hours spent by the students across all activities?