Small-business confidence hit a record high in 2017, according to the National Federation of Independent Businesses.

The right-leaning lobbying group on Tuesday released its latest index of small-business optimism, capping what it said was "an all-time record-setter" of a year.

The index came in at 104.9 in December. The NFIB says the index's average monthly level last year was 104.8, the highest in the history of its survey.

Ian Shepherdson, the chief economist at Pantheon Macroeconomics, said that while the group's headline number was encouraging, some of the underlying trends in owners' spending intentions were still lagging.

Shepherdson noted that the percentage of owners who say they are increasing capital expenditures — making large investments in their businesses — remained near a nine-month low in November.

Read more in Business Insider.