This part shall not apply to the following counties of this state having the following populations, according to the 1960 federal census or any subsequent federal census: 
 not less than  nor more than 
 5,100  5,200 
 8,500  8,600 
 9,500  9,570 
 10,700 10,800 
 12,075 12,100 
 12,300 12,350 
 12,500 12,550 
 14,700 15,400 
 16,000 16,500 
 17,000 17,500 
 18,000 18,500 
 21,500 21,750 
 24,500 25,000 
 36,000 37,000 
 41,560 41,685 
 52,000 53,000 
 56,000 57,000