The top-grossing U.S. law firms reported their best financial year since the great recession in 2018. But they aren't exactly spreading the wealth around.

Data analyzed by ALM Intelligence, a division of Law.com parent company ALM, shows that among partners at firms ranking in the Am Law 100 index, the percentage of equity partners has been steadily contracting for almost two decades.

That decline comes even while many firms have seen positive financial performance. The Am Law 100's average revenue per lawyer was up 4.2 percent in 2018 to almost $1 million—the fastest year-on-year growth since 2010. The average Am Law 100 equity partner brought in $1.88 million in profits in 2018, up 6.5 percent from the previous year.

David Altuna, a client adviser at Citi Private Bank Law Firm Group, told The American Lawyer last month that maintaining or shrinking the equity partner tier has become a trend—and that some firms are seeing an “upward lift” in profits from cutting partnership ranks.