If you define middle class solely by income (rather than accumulated wealth), and consider them "middle class" just from one year's worth of middle class level

If you define middle class solely by income (rather than accumulated wealth), and consider them "middle class" just from one year's worth of middle class level income (an abberation, basically), then this may be perhaps possible? I remember there was an article on HN that described such "income churn" for the population, and it was tremendous how people enter and exit mid to high income ranges throughout their lives.