Billboard Hot 100 Number Ones: 1980 Quiz

Every distinct song that appeared at No. 1 on a Billboard Hot 100 issue dated in 1980: 17 songs across 17 chart runs and the full calendar year. The issue-date scope includes a prior-year leader that returned to No. 1 during 1980. Name the complete roster, recognize the leader for a spread of changeover dates, match songs to artists, order a selection by its first 1980 date at the top, or separate the number ones from same-year Top 10 near-misses. No year-end ranking is implied.