1. Introduction

2. Quasar sample and redshift path
2.1. Redshift path
2.2. Quality of the spectra
2.3. Broad absorption line (BAL) quasars

3. Detection of DLAs and N(HI) measurements

4. Results
4.1. Sensitivity function
4.2. Importance of systematic effects
4.3. Frequency distribution
4.4. Convergence of Ω_g^DLA and the contribution of sub-damped Lyman-α systems
4.5. Evolution with cosmic time

5. Conclusion