To maintain reduced class sizes; purchase textbooks and teaching materials; attract and retain qualified teachers, aides and counselors; enhance core subjects including reading, writing, math, and science, and improve custodial services, shall West Contra Costa Unified School District be authorized to levy, for 5 years only beginning July 1, 2004, an annual tax of 6.8 cents per square foot of total building area or $6.80 per vacant parcel, with an exemption for eligible seniors?