from colorado code of regulations
not a real "number" of staff, but the general requirements...
part 7 - nursing services
7.1 organization. the facility shall have a department of nursing services that is formally organized to provide complete, effective care to each resident. the facility shall clearly define qualifications, authority, and responsibility of nursing personnel in written job descriptions.
7.3 24-hour nursing coverage. the facility shall be staffed with qualified nursing personnel, awake and on duty, who are familiar with the residents and their needs in a number sufficient to meet resident functional dependency, medical, and nursing needs.
7.3.1 staff shall be sufficient in number to provide prompt assistance to persons needing or potentially needing assistance, considering individual needs such as the risk of accidents, hazards, or other untoward events. staff shall provide such assistance.