It might have been >85% around here in the spring/early summer but over time I saw more and more people out in stores without masks. Who knows what the percentage was, I'm sure it varied with area.I do not believe that 85 percent for a second, for one. Still tons of people not wearing masks around me, which incidentally is an area that's been soaring to record levels and healthcare system crunch for months. And in a land where people still breed like it's an 18th century agricultural society, I'm quite sure those family/church/neighborhood gatherings are a factor. My family had to quarantine because of it.
Local health department here says contact tracing is leading back to gatherings in homes for many of the cases. Some in restaurants/bars, some from people going to work with symptoms.
I'm sure it's a combination of many things. Masks help but are not 100% effective. More people are indoors this time of year, it's a very contagious virus, people can spread without having symptoms - so I would expect cases would have risen regardless. But I think a large part of it is people got tired of following restrictions, became careless or even rebellious and had those close gatherings with others. Around here I suspect there was some complacency because infection rates in NY were so low for so long. And here we are.