The statement that correctly analyzes the effectiveness of Spanish colonial rule is:
Colonial rule was weakened by decreases in the indigenous population because there were fewer people to work in the colonies.
This is supported by the evidence in the quote, which indicates a drastic decline in the population from approximately 60 million to 6 million after Spanish arrival. This significant decrease would have resulted in fewer laborers available for work, undermining the colonial economy and potentially weakening the overall effectiveness of Spanish control.