How Many Wandering Monsters?

Okay, this is not about frequency of random encounters in a dungeon.  I delved into that here.  This is more about variety.  What I'm curious about now is: How many types of distinct creatures are on your wandering monster table?  And, also, how likely is it to encounter each?

I'm asking because I'm trying to streamline my DMing.  I was thinking of even pre-rolling encounters and having them appear one by one as encounters  occur (I'm pretty sure I saw this in action on Jim's Carjacked Seraphim blog).

I actually like better not knowing as a DM what will show up.  But I tend to forget how many stirge attacked the party, and in worst case scenarios I'll lose track of which creature had been hit/how many hp they have left during the combat because I'm just scrawling on scratch paper.  I've tried the using-8-siders to keep track but this assumes you have a nice clean space at a table to keep them separated from your regular dice.  I'm usually standing or even perched over a sliver of end table.

Anyway, if I have only 4 to 6 types of monsters to randomly encounter, maybe I can pre-roll several different batches of stirge and have them ready to roll.  So I'm wondering if your tables are sparse like that or tend to be d20 or d100 affairs.  Any other details on tracking hp/xp would be of great interest too.  Okay, I'm off to forage on the tundra (Skyrim).