Calculated over 600,000 years. The rarest is miketz read 10.1% (when rosh hashana is shabnos and year is chaser.)
Pinchas is 10.6% (a leap year when rosh hashana ws Thursday)
Kedoshim is read 11.1 % of time
Tazria is slightly more at 16% (read in leap year when rosh hashana was shabbos or monday and year is chaser)