Actually, it's complicated stuff pulling together two data points:
1) 2/3 of people are confident contributing in 2 months or less
2) And 50% of people are AS PRODUCTIVE IN RUST as they were in their other language within four months
Given that #2 is talking about people who are all professional programmers and where only a small percentage of respondents previously knew Rust, that's pretty amazing to me.
I'll see about whether I can push an update. Thanks for the catch!