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We have vastly increased the CIV statistics at intermediate redshift bysurveying the thousands of quasars in the Sloan Digital Sky Survey Data-Release7. We visually verified over 16,000 CIV systems with 1.46 < z < 4.55---a samplesize that renders Poisson error negligible. Detailed Monte Carlo simulationsshow we are approximately 50% complete down to rest equivalent widths W_r ~ 0.6\AA. We analyzed the sample as a whole and in ten small redshift bins withapproximately 1500 doublets each. The equivalent width frequency distributionsf(W_r) were well modeled by an exponential, with little evolution in shape. Incontrast with previous studies that modeled the frequency distribution as asingle power law, the fitted exponential gives a finite mass density for theCIV ions. The co-moving line density dN_CIV/dX evolved smoothly with redshift,increasing by a factor of 2.37+/-0.09 from z = 4.55 to 1.96, then plateauing atdN_CIV/dX ~ 0.34 for z = 1.96 to 1.46. Comparing our SDSS sample with z < 1(ultraviolet) and z > 5 (infrared) surveys, we see an approximately 10-foldincrease in dN_CIV/dX over z ~ 6 --> 0, for W_r >= 0.6 \AA. This suggests amonotonic and significant increase in the enrichment of gas outside galaxiesover the 12 Gyr lifetime of the universe.

Precious Metals in SDSS Quasar Spectra I: Tracking the Evolution of Strong, 1.5 < z < 4.5 CIV Absorbers with Thousands of Systems