That's not lifetime ROI. It's pretty obvious they mean annual, since they compare it to stocks returning 8% and we know that isn't a "lifetime" return. "Indeed

That's not lifetime ROI. It's pretty obvious they mean annual, since they compare it to stocks returning 8% and we know that isn't a "lifetime" return. "Indeed, by comparison, the stock market has provided a long-term return of about 8 percent and bonds have returned around 4 percent."