My guess
1988: Lean Bush
1992: Lean Clinton
1996: Strong Clinton
2000: 50/50
2004: 50/50
2008: Lean McCain
2012: Lean Romney
1988: Bush 52% Dukakis 47%
1992: Clinton 50% Bush 42% Perot 8%
1996: Clinton 53% Dole 44% Perot 3%
2000: Gore 49.9% Bush 49.8%
2004: Bush 50% Kerry 49%
2008: Obama 52% McCain 47%
2012: Romney 51% Obama 48%
This looks right, but I think you're underestimating G.W. Bush's share by 2-4% both times. The swing to Romney was quite pronounced among this group, which many seem to have overlooked.