Jeb! was riding high, on top of all the other Republican nominees at 15% in a crowded pack. He rode that early lead all the way to the White House by defeating Hillary.
Oh, wait...
June 2015 was the first time ANY national poll tracked Donald Trump.
By July 2015, Trump had passed Bush and taken the lead.
Trump has been polled for 3.5 years now, and his two most recent polls show just 37% against Beto and Bernie.