Unfortunately, it is in the nature of the archaeological evidence, which is almost invariable only a sample of what once existed, that such figures will always be elusive.

To find out, you'd have to take a systematic and unbiased sample – perhaps a whole week's worth of stories – and then check the evidence behind every claim.

If they have a cough, they will be asked to provide a sample of sputum, which will be tested for evidence of TB.