So goes Jan so goes the year, page-5

I'll answer my own question as dax was boring me like usual so drew them up .
The pattern previously explained did not exist pre 2000 era . Some years may of but no where near consistent enuff to call it based on July colours . But post 2000 the pattern is quite clear to me . I wonder if it was the result of change to xjo but can't remember what year we changed .