I just listened to it.
The verses are the following chord progression:
Code:
Am | F | G | D
Am | F | E | Am
The bass is playing a basic pattern over each chord that is something like this:
So, for example, over the Am chord, it would be this:
There are a couple of fills here and there, but that pattern is the meat of the bass line for the verse.
The choruses are the following chord progression:
Code:
C G | F C | G | % |
C G | F C | G | E |
The basic bass pattern for each chord is mostly R R 3 5. So over the first measure of the chorus, which is a C chord and a G chord, the bass is playing C C E G G G B D.
Over the second measure, it sounds like he switches the pattern on the F chord to R 3 5 3, and then back to R R 3 5 on the C chord. So, he is playing F A C A C C E G. (By switching up the arpeggio pattern on the F chord, he avoids playing the C note three times in a row, and creates some additional movement in the line.)
Etc.
The tab in the link posted by funnyfingers has some mistakes. The arpeggio in the introduction is a guitar, not bass. (The bass plays an E on beat 4.) The tabbed bass line in the verses is not what is on the recording, and also shows an A major arpeggio in the first measure, when the chord is an A minor. I would encourage you to use what I've sketched out above and work out the line for yourself rather than rely on inaccurate tabs.