Unfortunately, I no longer have these data. I locked them away in my university account years ago, and haven't looked at them for a long while. They've probably been purged from the account already I'm guessing. However, I do recall that the distribution isn't all that "normal." IF I remember correctly, the Chi-Squared Test of fitness only scored around 0.85. I believe Peters (Fractal Market Analysis) came up with some Fractal Distribution. In all seriousness, I think this is just another Black Scholes at best, and Wizetrade behind equations at worst.