Middle-class squeeze?

So, after hearing all my life about the middle class getting shafted, and taxed into oblivion....it appears that we may be doing better after all:

Let's examine the Census numbers. They certainly don't indicate that, over any reasonable period, middle-class living standards have stagnated. Mostly, the middle class is getting richer. Consider: in 2003, 44 percent of U.S. households had before-tax incomes exceeding $50,000; about 15 percent had incomes of more than $100,000 (they're also included in the 44 percent). In 1990 the comparable figures were 40 percent and 10 percent. In 1980 they were 35 percent and 6 percent. All comparisons are adjusted for inflation.

It appears the influx of immigrants may be dragging down that all-important "median income" average everyone likes to quote. The above in table format makes it clearer:

Year 50k+ 100k+
2003 44% 15%
1990 40% 10%
1980 35% 6%