Statistical sensitivity function of our C i survey, g(z) (solid curve; left-hand axis). The dips seen at z ~ 2.35 (resp. 2.6) are caused by C i λ1656 (resp. C i λ1560) falling over bad pixels at the junction between the two SDSS CCD chips. Dips at higher redshifts (z ~ 2.8,3.05) are due to telluric lines (e.g., [O i] λ6300). The histogram (right-hand axis) shows the C i-absorber number counts in different redshift bins for intervening systems with rest-frame equivalent width above our completeness limit, i.e., W_r(λ1560) ≥ 0.4 Å.