This simply isn't true. In fact it's so far from the truth it hurts my brain. Well written Lisp applications are in large part (and sometimes mostly) macros. PG once mentioned that the ITA guys said over half of their codebase is (was?) macros.
For my own code, it consists of maybe 10% macros. I would say the same is true for PG's code (for the hacker news app- The arc core libraries have more macros but are a special case.)
Unless, of course, if you mean _calling_ macros- I would agree that Lisp code often has 50% of its calls be macro calls instead of function calls.
Macros are like 2nd-amendment rights. You hope you never have to use them, but when you do you'd be in a world of hurt without them.