The Nintendo Switch’s software attach rate is higher than the Wii’s, and it’s seen a significant rise in sales per hardware unit year by year, Nintendo reported on Thursday.

Cumulative sales per hardware unit for the Nintendo Switch reached 55,000 yen in its third fiscal year. The Nintendo Wii reached 42,100 yen in its third fiscal year, for comparison. Those figures include hardware and software sales, sales of accessories like Joy-Con controllers and the Nintendo Switch Pro Controller, sales of titles from other software publishers physically manufactured by Nintendo on commission, add-on content sold digitally, and Nintendo Switch Online revenue.

Nintendo is basing its claims off of a different metric than the one traditionally used by video game publishers. Conventionally, they calculate the attach rate of software per unit of hardware by dividing the number of software units sold by the number of hardware units sold. But, Nintendo said that method no longer adequately reflects the state of its business because of the rapid growth of digital sales, which includes indie titles with differing price points and add-on content that can’t be counted with the number of software units sold.

So, Nintendo is now basing its software attach rate on “sales per hardware unit,” which is the overall sales for the platform divided by sales of the hardware itself. “Note that this is calculated based on sales recognized by the company, and it differs from individual consumer spending,” the company said.

“A straightforward comparison is difficult due to the original prices and bundle specifications of Nintendo Switch and Wii hardware being different,” it said. “That said, you can see that Nintendo Switch has seen a significant rise in sales per hardware unit year by year, and sales are higher than for Wii.”

Nintendo reported it sold about 2.5 million Switch consoles in the fourth fiscal quarter, which ended in March. That brings the total number of systems sold for the fiscal year to just under 17 million. The company has sold an estimated 34.74 million Switch units since its release in March 2017, surpassing the Nintendo 64’s lifetime sales but making up only about a third of the Wii’s lifetime sales.