Authentic Pfizer spam?

I am reasonably sure you would've seen/received umpteen of spam emails from "Authentic Viagra Sellers" or some-similar-sounding-spammer kin, with the subject announcing a flattering personal/special discount of 80% off Pfizer.
It's needless to say that the subsequent action one takes is simply to delete this stupid spam. Which is what I did a few hours ago too, in my usual nonchalant way. I did a "Select: All" first and then, as I hit the "Delete forever" button, out of the corner of my eye, I noticed the subject of one of these Pfizer spams... offering a discount of 73% !!! How on the earth did they choose this number? :D
Or has it been this way and it's only that I noticed this today?

Whatever, must say I feel a bit dejected on having deleted that email now! :D