Month

Monthly averages 1978-1989

Monthly averages 1990-2001

1

15.5

16.2

2

15.1

15.3

3

15.6

15.6

4

17.2

17.2

5

19.4

19.9

6

21.2

21.9

7

22.6

23.8

8

23.4

25.0

9

23.4

24.7

10

22.9

24.0

11

20.7

21.4

12

17.7

18.2