Drop rates

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1	Click on one of the sheets below to see the drop info for each area.
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3	Drop rates in Prime 1 aren't determined by the type of enemy; rather, they're based on the room, and enemies can be assigned to a "Pickup Generator" in that room. Many rooms have multiple Generators, for different groups of enemies.
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6	Each drop (Small Energy, Large Energy, Missile, Power Bomb, Ultra Energy) in a group has a number, and a percent chance of dropping based on that number. The numbers were taken straight from the game data; the percent chance is JUST AN ASSUMPTION, based on dividing the number of a drop by the Total of all drop numbers in that group.
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8	If you don't have Missiles or Power Bombs, I'm assuming that they're ignored and their numbers don't count towards the total, meaning there's a greater chance of getting everything else instead of a chance of getting nothing. This means that the percents given for groups that contain PBs is incorrect when you don't have PBs, etc.
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11	The Frequency is a bit difficult to explain. Basically, there isn't a percent chance of whether something can be dropped, period; whether an enemy will drop something is fixed, and is based on how many enemies in that group you've killed already. The way it works is:
12	- Divide 100 by the Frequency, to get the starting value.
13	- - - For example, if the Frequency is 40, 100 / 40 = 2.5.
14	- Whenever an enemy is killed, this value decreases by 1. When it reaches 0, it loops back to the starting value.
15	- - - 2.5, 1.5, 0.5, (loops to 2.5 at 0) 2, 1, (loops again) 2.5, 1.5, 0.5...
16	- If this value is GREATER than (not equal to) 1, prior to it being decreased, then the enemy drops something.
17	- - - Yes, yes, no, yes, no, yes, yes, no...
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19	There are some situations where nothing is dropped when there should be according to the Frequency. Usually, it's because that source can't drop missiles when you're full on missiles, PBs when you're full on PBs, etc.; however, certain sources can also drop nothing for seemingly no reason. I'm not sure what causes this.
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21	- The first enemy in a group will always drop something (aside from the situations mentioned above).
22	- Higher Frequency values means that drops occur less often, and vice versa. Really high values (such as 95) are usually used for groups like Scarabs, that come in large swarms.
23	- A Frequency of 0 means that something is always dropped.
24	- The total for the drops in a group and the frequency usually add up to 100. This doesn't seem to be necessary, though, so I'm not sure what the purpose is.
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27	Some groups are unused. For groups that say "[Enemy] (Unused)", this means that the enemies are part of an unused room layer. For ones that just say "Unused", this means that the group isn't assigned to any enemies at all, as far as I can tell.