The graph given below shows the sales of books (in thousands) of four branches of ABC Publishing Company in two consecutive years. What is the ratio of the total sales of branch P2 for both the years to the total sales of branch P4 for both the years?
1
61 ∶ 71
2
17 ∶ 16
3
16 ∶ 17
4
71 ∶ 61