I believed the analyst counted the votes on the first round of voting in the two primaries. After that, candidates started dropping off. Voters for those candidates had to vote someone else.

I believe this "math" was done for all eligible voters. As you know, many Americans do not participate in the primaries, but vote in the general election. And many Americans don't vote.

In the end, the 92% had only two choices: Mr. Clinton or Mr. Trump.