More than 31 census records are available for the DeCoste family, from both 1901 and 1911.
Sample 1901 Argenteuil census records about the DeCoste family available from Ancestry.ca:
A DeCoste family household of at least 9 members residing in the district of Argenteuil was recorded in 1901. The head of household, Alex DeCoste, was born in Quebec in 1857. He identified his heritage as French. By 1901, at the age of 43, he had an occupation that was recorded as "Laborer". Alex's wife was Delina DeCoste, who was 36 years old. Delina was born in Quebec in 1864. She also identified her heritage as French. Alex and Delina had 7 children, 3 boys and 4 girls. In 1884 their eldest child, a girl named Delina, was born. Three years later, in 1887, when Alex was 30 years old and Delina was 23 years old their second daughter, who was named Delima, was born. Then, in 1888, with their two older daughters ages 4 years and 1 year, their third daughter, Eva, was born. Alex and Delina's first son was born in 1890 and was named Arthur. With four other children in the household, their fifth child and fourth girl, Julia, was born in 1891. She was followed by 2 more children: their son Napoleon, born in 1894; and their son Leduas, born in 1898. Thus, at the time of the 1901 census, this DeCoste family household was filled with 7 children whose ages were 3, 7, 9, 10, 12, 14, and 16 years.