75% of my business are sellers. I market myself as a Sellers Agent though. From time to time I do get calls regarding some of my listings & actually get to work as buyers agent also. I don't know if there is a perfect ratio for an agent. I would always like to have more buyers so I wouldn't be so dependent on other agents selling my listings. Not to mention the fact that I make more money by representing both sides in a dual agency role.
Good Luck & God Bless