The percentage you see is percentage of votes, not population.
Those are votes cast for one party or another. The Democratic plus margin in votes cast - about 7 percent, is reasonably close to the percentage of seats picked up by the Democrats - about 5 percent.
I don't know the source of that Wiki number, or if it's even correct.
The actual makeup of the whole state is not easy to find, since Michigan does not make party affiliation part of their registration. If you go by exit polls, it comes out about 40 percent Democrats, 33 percent Republican, and 27 percent Independent. And of course, exit polls count the people who actually vote, not registered voters, or population in general.
There's no conspiracy.