During the process of collecting the data of reading fortnightly magazines

A, B and C, a survey company surveyed 20,000 families. The company

found that 20% families read magazine A, 40% families read magazine B,

and 10% families read magazine C, 5% families read A and B, 3% read B

and C and 4% read A and C. If 2% families read all the three magazines,

then the percentage of the families who read magazine B only