Extract enrollment denominators and age breakdowns

Extract enrollment denominators and age breakdowns

For each trial, extract the total enrolled, the number aged 75 and over, and where in the publication each value appears. Record trials reporting only a mean age, or no age breakdown, as unreported rather than estimating. Deliverable: A CSV with trial, registration_id, total_enrolled, enrolled_75_plus, source_location, and age_reporting status.