Gail, it is possible that many of those who attend your readings already have your book and that is why they are there.
But for sure, the economics apply.
From where I sit the dollar is half worth (one dollar is 6.2 kronor this morning) what it was when I was in the states (one dollar cost 12 kronor then). Consequently, I am buying more books than I usually do. And I think I'll go fishing at a contest or two and hope it goes up before I win

. But only IF.
I still believe in the old adage,
Build a better mousetrap and the world will beat a path to your door. (I don't build 'em, I buy 'em.)