U.S. corporations are contributing the smallest share of federal tax revenue in a generation.

That’s one of the findings in the Data Book for 2018, released by the Internal Revenue Service on Monday. In the fiscal year covered, the IRS processed more than 250 million tax returns and collected nearly $3.5 trillion in federal taxes paid by households and businesses.

The data show that the burden is increasingly falling on individuals. Their income taxes account for about $1.95 trillion, or 57% of total revenue. An additional 33% came from employment taxes. Corporations only paid 7.6% of the tax take -- the lowest share since at least 1960, according to the IRS data.

After adjusting for refunds, the share may be even lower. Businesses got more than $60 billion back from the IRS, lowering the net collection amount to $202.7 billion.

The IRS report also provided data on tax audits and taxpayer attitudes. About two-thirds of respondents agreed that it’s their civic duty to pay their fair share of taxes, and an even bigger majority said that it’s not acceptable to cheat.

There were some outliers, though. About 3 in 100 taxpayers said it’s acceptable to cheat “as much as possible.”