An important piece of modern (4G/5G) cell network design is that cells can have overlapping coverage to provide extra capacity in an area. The top level statistic that 52% of sites were down does not necessarily mean that 52% of the area was out of coverage at that time. It would be very expensive to heavily reinforce every small cell in every neighborhood for a large scale disaster, but would make sense to reinforce enough macro sites with wide area coverage to maintain low bandwidth emergency communications (voice+text) across the entire region.