What was the most popular book in 1970?

In 1928, according to Publisher's Weekly, the best-selling fiction books included "The Bridge of San Luis Rey" by Thornton Wilder; "Wintersmoon" by Hugh Walpole; and "Swan Song" by John Galsworthy. Among non-fiction books, one that was attracting attention was "Coming of Age in Samoa" by anthropologist Margaret Mead.