The BBC has nailed down something I've vaguely wondered since reading in Arthur C. Clarke's 2001 that the dead outnumbered the living 30-to-1. Now, the ratio is more like 12-to-1! Some 83.2 billion have lived since the beginning of the species, and about 7 billion of them (us) are alive now.
Next question: how many people have lived/died in the last 100 years? 10 billion, according to the BBC. 200? 500? A disproportionate slice of human history, viewed in terms of hours lived by human beings, has happened quite recently. And as I've suggested before, it's quite right that kids read less of the classics and spend more of their educational time soaking up what's been written and discovered in recent times than they would have done 50 or 100 years ago -- since the percentage of literate people and those who have added to the permanent store of human knowledge or preserved human expression in the past 150 or 100 or 50 years must be many times that of the percentage of people who have lived within those time frames.