When was the American middle cl the stongest? When unions were strongest.?

A solid argument could be made about the strength of the middle cl and the stregth of unions. In post WWII America the American middle cl was very strong and Americans had 25% union membership. Yet since Reagan declared that we are a country for the corporation, not the people, the middle cl has steadily declined. EVERY metric indicates this. Relative wages have gone down, as well as the standard of living. The middle cl now make a tiny fraction of what CEO's earn. There is no middle cl really. We now have ~12% union membership. Seems hard to justify the hypothesis that "greedy union thugs" (like those "thug" teachers as they have been called lately) are really causing all the problems.