The 1000 Genomes Project created what they defined as accessibilty masks for the pilot phase, phase 1 and phase 3 of the Project.
The pilot mask showed that only 85% of the genome is accessible to accurate analysis with the short read technology used by the 1000 Genomes pilot project. The remaining 15% is either repeats or segmental duplications. There is more information about the pilot mask in README.callability_masks.
For the phase 1 analysis using the pilot callability criteria 94% of the genome was accessible. A stricter mask was also created for the phase 1 project to be used for population genetics analysis; this mask used a narrower band of coverage criteria and also insisted that less than 0.1% of reads have a mapping quality of 0 and the average mapping quality should be 56 or higher. These criteria lead to 72.2% of the genome being accessible to accurate analysis with the short read technology used at that time by the 1000 Genomes Project. Further information is in section 10.4 of the supplementary material from the phase 1 publication.
In phase 3, using the pilot criteria 95.9% of the genome was found to be accessible. For the stricter mask created during phase 3, 76.9% was found to be accessible. A detailed description of the accessibility masks created during phase 3, the final phase of the Project, can be found in section 9.2 of the supplementary material for the main publication. The percentages quoted are for non-N bases.