Curiosities of Ancestry's Ontario Death Collection

Searching Ancestry's database Ontario, Canada, Deaths, 1826-1938 year-by-year yielded the data for the blue line in the graph.

The red line is from data in Province of Ontario - Vital Statistics available in annual reports at the Internet Archive - https://archive.org/details/ontariovitalstats.

Why overall does Ancestry have 10.7% more records than in the official record from which it's derived?

The two records track closely until 1900 except for 1889-91 — 1890 was an influenza year.

Through the first decade of the 20th-century Ancestry's database grows, 25% more entries than the official record in 1910, 37% larger in 1914, remaining nearly 30% larger until 1920.

There are two unusual peak death years in the Ancestry database in 1929 and 1944. The latter is likely the result of including overseas war deaths of Ontario servicemen and servicewomen.

It's unusual to find people named in Ontario's annual report of births, marriages and deaths; 1880 is an exception where the following list of centenarians who died is included on page 60.

In only 9 of the 29 could I confidently identify them in the 1871 census where on average they were born 3.5 years later than would be implied by the death information.