Scrolling speed for titles

So, I'm working on a credit sequence in FCPX and it's composed of several scrolling titles due to needing to format blocks of text differently. I'm wondering how to get each title to scroll at the same rate. I know that scroll speed is dependent on the length of the clip, but has anyone figured out a formula in terms of seconds per line of text to get things to scroll uniformly?

Thanks!

Timing depends on the duration of the clip, and the number of text lines, there's no real math formula for this. It's just trial and error tweaking.