Number of ORFs that are >100 and 300 bases, respectively, for each chromosome, as a function of the chromosome length. The regression lines have the slopes 3.7924 ± 0.0285 and 0.6058 ± 0.0067. The regression accounts for 99.9% and 99.8% of the variances, respectively, indicating an almost perfect modeling of the data with the linear function. The regression analysis is performed using the statistical package S-PLUS v. 3.4.