Multigenerational homes and extended family care would not be counted as “single parent” in this study
Its more of a “one adult in the house” study
The numbers are percentages, so why would total population matter?
I interpreted that comment as "Its remarkable that India has a lower total number with so much population," implying that the rate is drastically lower."
On top of the other points, like in many other conservative cultures, much of the population leans towards staying in a bad relationship if already married because divorce is seen as worse than being a dysfunctional family, especially for women.