1273
The proportion of infants who were vaccinated in January and February 2000 ( 48 . 5 % and 67 . 5 % , respectively ) was less than any other months , whereas the proportion who were vaccinated in December 2000 ( 88 . 2 % ) was the highest .
 None
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Disease, Chemical 
Text: {0} 
Answer:
 None