Even as the economy grew, incomes stagnated last year and the poverty rate rose, the Census Bureau reported Tuesday. It was the first time on record that household incomes failed to increase for five straight years. Over all, the poverty rate increased to 12.7 percent, from 12.5 percent in 2003. Poverty levels have changed only modestly in the last three decades, rising in the 1980's and falling in the 1990's, after having dropped sharply in the 1960's. They reached a low of 11.1 percent in 1973, from more than 22 percent in 1960.