Ted Cruz has 28% of the primary vote right now. The only percentages lower than that by a winner were back before every state even had votes.
Cruz winning would be the ultimate pyrrhic victory. He'd inevitably lose in November, and never be relevant in presidential politics again, be in 2020, 2024, etc. Cruz would forever be that guy that overturned the will of the people and allowed Clinton into the White House.
Mitt Romney in 2012: 52.13% of the primary vote
John McCain in 2008: 47.32% of the primary vote
George W. Bush in 2000: 62.00% of the primary vote
Bob Dole in 1996: 58.82% of the primary vote
Where are trumps numbers