The nature of exponential growth is such that no matter when you test, 50% will have gotten it within the last doubling period. If it’s doubling every three days, half have caught it in the last 3 days, 75% in the last 6 days, 86% in the last 9 and so on. Given the long incubation period it makes sense that the vast majority are currently asymptomatic. I think that will be the case at every point during exponential growth, even if the ultimates fatality rate is quite high.