Finders fee percentage for bringing in investors?

[Anders Jax]

What kind of percent would be fair to command for bringing investors to the table for deals?

4% first million, 3% next million, 2% next million, 1% thereafter?

What duration would you hold those percentages for (to avoid getting backdoored after a single small deal)? 2 years? 10? 

Nobody is going to intro a heavy investor and have them put $100k on one deal, you get paid, then do a $10m deal a month later and get nothing.