Learn English – Which tense when talking about books

When you are presenting the table, you are doing it now, i.e. in the present time. The clue is in the word PRESENTing. But the table itself contains data that has already been collected - in the past.

So you are correct in presenting the table in the present tense, but discussing the previously collected data in the past tense.

This is a long-standing case were the present historic is often used. It is though also a case were the past historic has long use.

You may freely use either. The same incidentally applies to descriptions of the writer's approach and technique, etc. (Slightly more controversially; a recent increase in use of the present historical for non-fictional elements has brought a backlash from some, though they'd mostly say it was a valid choice they disliked rather than wrong).

Some use the past historic generally, but highlight some parts by switching to present historic. Done well this can be very effective, but that gets into stuff probably more on-topic on the writers' site than here.