While it is true that the LDS leaders were much more likely to have plural women & girls (wealthier men who could afford them; plus greater pressure on leaders & future leaders to do so by those already engaged in the practice), that amounted to still a high percentage.
B. Carmon Hardy estimates that during its peak in the late 19th century, 20-30% of Mormons were part of polygamous families. (LDS have often intentionally skewed these stats by counting percentages among men...but, if, say, the average polygamous man had 3 wives...you automatically dilute the %).
Even 20% or 30%, if that “estimate” is even remotely accurate, is not a “high percentage.”