Calculating Total Rainfall from a Line Graph

At Riverwood School, students participated in a science experiment where they recorded the amount of rainfall over a week. The results were compiled into a line graph that shows the rainfall in millimeters each day:

Day 1: 5 mm

Day 2: 10 mm

Day 3: 8 mm

Day 4: 15 mm

Day 5: 7 mm

Day 6: 12 mm

Day 7: 4 mm

The total rainfall over the week is calculated by adding the daily amounts. What was the total rainfall recorded at Riverwood School over the week?