Fig. 3From: Characterization and analysis of an infectious bronchitis virus strain isolated from southern China in 2013Proportion of TW-type domestic strains in recent years in China. Each denominator (224, 146, 251, 59) represent the numbers of IBV strains during different years, while the numerator (4, 10, 12, 8) represent the numbers of TW-type strains. All the data used were from NCBIBack to article page