Each HOA establishes their own CCRs, and the CCRs can be changed by amendment. I can't imagine that any state law would require that a HOA have a certain % of renters to owners.
So get out your CCRs & read them.
Washington law does not place a statutory cap on the percentage of renters in either condominium or homeowners' associations. Each association has the ability to adopt a rental cap (or even an outright rental restriction) in their CC&Rs or Declaration. If your association does not already have a rental cap in your CC&Rs, the only way your association can adopt a cap is by amending the CC&Rs. The process for adopting such an amendment is described in your CC&Rs, and an attorney experienced in community association law can assist you in drafting the amendment and navigating the adoption process.