How do I create a consistent time gap between many audio clips?

I have about 30 audio clips of different durations. I'd like to insert an 8-second gap between each clip (i.e. 8 seconds from the end of one clip til the beginning of the next clip.) What's the most efficient way for me to achieve this? Currently I copy & paste a silent 8-second audio clip 29 times and then manually drag and insert it between all my real audio clips. It's quite a pain.

You don't need to add a clip. Just hit Option W and that will insert a gap.  You can set the default length in the prefs or hit CTRL D and type in the duration you need. 

In addition: once you have all your gaps you can open the timeline index, search for gaps so the list only shows your gap clips, select them all and hit control-d to set the duration of all of them at once