1. HARRY POTTER , by J.K. ROWING - 7 = 450,000,000

2.GOOSEBUMPS, by R.L.STINE - 62 + spin off series = 350,000,000

3.PERRY MASON, by ERLE STANLEY GARDNER - 82 = 300,000,000

4.BERENSTAIN BEARS , by STAN & JAN BERENSTAIN - 260,000,000

5.THE RAILWAY SERIES , by REV. W. AWDRY  & CHRISTOPHER AWDRY - 41 = 200,000,000

5.NODDY , by  ENID BLYTON - 24 = 200,000,000

7.THE BABY-SITTERS CLUB , by ANN MARTIN - 335 = 172,000,000

8.PETER RABBIT , by BEATRIX POTTER - 6 = 150,000,000

9.CHICKEN SOUP FOR THE SOUL , by JACK CRANFIELD  MARK VICTOR HANSEN - 105 = 130,000,000

10.FRANK MERIWELL, by GILBERT PATTEN - 209 = 125,000,000