Cover of the Year

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Key: 

         Formal = F

         Environmental = E

         Informal = I

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1 - F

2 - F

3 - E

4 - F

5 - E

6 - F

7 - E

8- I

9 - F

10 - F

11 - E

12 - I

13 - I

14 - E

15 - F

16 - F

17 - E 

18 - I