Orbital period distribution of all pre-bounce CVs. We also show the distributions of pre-bounce CVs with WDs older than 2, 2.5, and 3 Gyr. The overall fractions of systems with WDs older than 2, 2.5, and 3 Gyr are 36%, 23%, 16%, respectively. Above the period gap (i.e., P_orb ≳ 3 h), the same fractions are 12%, 9%, and 6%, while for systems inside and below the gap, they are 45%, 27%, and 20%.