Are you just cycling letters through the years? This year is H, last year is G, next year is I kind of thing?

_{I'm kind of curious as to why you picked that method rather than using the actual year but I'm sure there's a madness to your method ;D}

I've kind of pseudocoded how to do it in my head (including a possibly separate script to correct any possible miscounts by the publish date) but as you're not using a stack I'm familiar with I'm not sure how to actually write it x_x