How many years was Boo Radley locked inside his house in To Kill a Mockingbird?

initially got into some trouble thatrefers to as "running with the wrong crowd" and
was arrested on charges of disorderly conduct and disturbing the peace. Mr. Radley insisted that
he be allowed to take Arthur (Boo) home and that he would never bother anyone again. After this,
it was 15 years before anyone saw him again.

Miss Stephanie insists (through
her typical gossipy manner) that one day Mr. Radley came running from the house, insisting that
Boo had stabbed him in the leg and was going to kill them all. He was taken to the courthouse
basement for a while but was again released back to his father, who seemed to keep him locked in
the house upon his return:

Nobody knew what form of
intimidation Mr. Radley employed to keep Boo out of sight, butfigured that Mr. Radley kept him
chained to the bed most of the time.said no, it wasn't that sort of thing, that there were other
ways of making people into ghosts.

Whatever tactics his
father used, Arthur never comes out of his...