Billionaire Steve Ballmer said Friday that government data show it’s not clear whether tax policy will have an impact on business investment.

Ballmer, founder of a nonpartisan database for government statistics, told CNBC’s “Squawk Box” that his USAFacts group looked at capital investment and research and development.

“No matter what tax policy we’ve seen, it more or less increases linearly over time. It does not spike up. It does not spike down,” he said. “I won’t draw a conclusion, but the question is can that be really stimulated?”

The LA Clippers owner and former Microsoft CEO spoke after the Office of Management and Budget director talked about the Trump administration’s plan to achieve sustained economic growth.

Mick Mulvaney wrote in a Wall Street Journal op-ed published Thursday that the U.S. can achieve 3 percent GDP growth by cutting taxes, reforming welfare programs, investing in infrastructure, initiating new trade deals, and curbing government spending, among other things.

A major tax overhaul was a hallmark of Trump’s campaign, and some analysts say its pending arrival is partly the reason for the stock market’s rise.

As of Thursday’s close, the Dow Jones industrial average has surged more than 17 percent, the S&P 500 has gained 14 percent and the Nasdaq composite has risen 20 percent since the election.

On Thursday, Federal Reserve Chair Janet Yellen told Congress she doesn’t believe Trump’s plan will be enough to achieve that growth.