Ratios of Various Fortifications to Troops

Ballistae to Traps = 1:5

This means that for every 1 Ballista that you lose 5 Traps will get consumed.

So without further ado, here's the data I have:

TRAPS
Rookies to Traps = 1:1
Scouts to Traps = 1:1
Pikemen to Traps = 1:1
Swordsmen to Traps = 1:1
Cuirassiers to Traps = 1:2
Ballistae to Traps = 1:5
Battering Rams to Traps = 1:10

BARRICADES
Rookies to Barricades = 3.6:1
Pikemen to Barricades = 2.4:1
Archers to Barricades = 2.9:1
Cavalries to Barricades = 1:1
Cuirassiers to Barricades = 1:2
Battering Rams to Barricades = 1:7.2

ROLLING LOGS
Rookies to Rolling Logs = 1.6:1
Swordmen to Rolling Logs = 2.57:1 (I had to double-check this, but yes, they are worse than Rookies)
Cavalry to Rolling Logs = 1:2
Cuirassier to Rolling Logs = 1:5
Battering Rams to Rollings Logs = 1:33.3

ROCKFALL
Rookies to Rockfall = 2:1
Swordmen to Rockfall = 1.2:1
Cavalry to Rockfall = 1:2
Cuirassier to Rockfall = 1:2.6
Battering Rams to Rockfall = 1:1