1. INTRODUCTION  
2. DESCRIPTION OF THE SAMPLE  
3. DATA ANALYSIS  
4. OBSERVED $N_{\mathrm{H}}$ DISTRIBUTION  
5. INTRINSIC $N_{\mathrm{H}}$ DISTRIBUTION AND FRACTION OF CT AGN  
6. FRACTION OF ABSORBED SOURCES  
7. SOURCE COUNTS AS A FUNCTION OF $N_{\mathrm{H}}$  
8. DISCUSSION  
9. CONCLUSIONS  