Here are the banners for our back to school sale. They are listed in the order of highest-to-lowest click through rates.
Medium Rectangle (300x250, 40% frequency, 0.13% CTR)
Leaderboard (728x90, 25% frequency, 0.08% CTR)
Mobile Leaderboard (320x50, 12% frequency, 1.2% CTR)
Halfpage (300x600, 5% frequency, 0.23% CTR)
Large Rectangle (336x280, 1% frequency, 0.33% CTR)