Without examining the data, I can't verify, but it could work out like this:

Wisconsin: 60% North European, 20% West European, 20% Hispanic
Average North European score: 100
Average West European score: 100
Average Hispanic score: 80
Wisconsin Average: 96

Texas: 20% North European, 30% West European, 50% Hispanic
Average North European score: 105
Average West European score: 105
Average Hispanic score: 85
Texas Average: 95