The first number column is "seats per state". The second number column is "combined percentage of representatives" - PA and OH each have 5 representatives, so c

The first number column is "seats per state". The second number column is "combined percentage of representatives" - PA and OH each have 5 representatives, so combined they have (5+5)/150 = 6.7% of the representation. The third column is, I presume, the percentage of economic activity (GDP?) totaled among those states.