The equally interesting question would be "What average percentage of your net income goes towards equipment and software (LPs, CDs, DVDs, etc.) over a period of, say, the last few years". Or, the simpler version: "Is there a household item on which you spend more money than on audio/home theater equipment and associated software" (in my case, the answer seems to be "no" as I recently found out - I am not sure whether to my delight or dismay).
Most of us build up their system over time so the sum of the new equipment prices can become quite a high percentage of one's annual income. As we expericence sooner or later, the value of our systems in terms of resell value is typically much lower than what we originally paid (unless you kept some vintage tube gear around for a few decades).
To answer your question: A year's income would not buy my system at list price - but I bought much of my stuff second-hand or at a heavy discount.
