Well he got part of this right. About 25% of the country does self-identify as Republican. Where is he wrong is its the same for Democrats. See Gallup polling here
Keep in mind though, that Gallup polling is for all adults. If you look at likely voters, it's typically mid 30s for all 3 in a presidential year and upper 30s for D/Rs in non-presidential year with the balance from independents.