The function $P(h)=-0.05h^2+10h+500$ gives the predicted population $P(h)$ of a certain bacteria, in thousands, $h$ hours after an experiment began. If $P(70)$ is approximately equal to $850$, this means that after $70$ hours, the predicted population of bacteria was approximately $850$ thousand. According to this interpretation, what was the predicted population of bacteria, in thousands, after $70$ hours?