Ballista/Trans needed to Attack Lvl 1-5 NPC's

I'll start out the list of how many Ballista/Transports you need for NPC's. You also NEED archery and horseback riding researched to the level stated below to get NO losses.

Level 1: 10 Ballista 28 Transports (Archery Lvl.7)
Level 2: 36 Ballista 56 Transports (Archery Lvl.7)
Level 3: 150 Ballista 150 Transports (Archery Lvl.7)
Level 4: 200 Ballista 300 Transports (Archery Lvl.7)
Level 5: 400 Ballista 455 Transports (Archery Lvl.9 & Horseback Riding Lvl.8 )

Thats as high as I attack. JLSparky7 and I just had the conversation that Lvl.6-9 are not worth attacking to plunder resources because you are going to have losses no matter what. Lvl.10 NPC on the other hand is worth attacking as long as you can take it over and I'm sure JLSparky7 will start a thread about how to conquer a Lvl.10 NPC. Any questions just ask! I attack 20 Lvl. 4-5 NPC's everyday.