Billboard Hot 100 Number Ones: 2000 Quiz

Every distinct song that appeared at No. 1 on a Billboard Hot 100 issue dated in 2000: 18 songs across 19 chart runs and the full calendar year. The issue-date scope includes a prior-year leader that remained at No. 1 during 2000. Name the complete roster, recognize the leader for a spread of changeover dates, match songs to artists, order a selection by its first 2000 date at the top, or separate the number ones from same-year Hot 100 non-winners. No year-end ranking is implied.