It was 30% in the end, before the nomination it famously gave him a 2% chance of getting nominated. All the talk about 30% is disingenuous

https://en.wikipedia.org/wiki/FiveThirtyEight#2016_U.S._elec...

They had him at 30% at a time when most reputable media had him in single digits at best. You might not remember now, but the result of that election was a real shock.