Trusts which are entitled to the exemption from limitation as to their duration provided for in RCW 49.64.010 must be:

(1) Created by an employer primarily for the benefit of some or all of the employees of such employer or the families or appointees of such employees, under any pension, profit-sharing, stock bonus, retirement, disability, death benefit or other similar types of employee-benefit plans; and

(2) Contributed to by the employer or employees or both; and

(3) Existing for the purpose of distributing to or for the benefit of some or all of such employees (either before or after their employment ceases), their families or appointees, the earnings or principal, or earnings and principal, of the trust.