Why less than 10 turns per year in Solo?

[obiwanjohn]

Can someone explain the reasoning behind not having 10 turns per year in Solo?

[Cwali]

5 players: Year 1: 7 turns. Year 2: 7 turns. Year 3: 7 turns. So 21 turns.
4 players: Year 1: 8 turns. Year 2: 7 turns. Year 3: 7 turns. So 22 turns.
3 players: Year 1: 9 turns. Year 2: 7 turns. Year 3: 7 turns. So 23 turns.
2 players: Year 1: 10 turns. Year 2: 7 turns. Year 3: 7 turns. So 24 turns.
1 player: No Year Goals, so just 25 turns.