Japan retained its lead in per-capita savings last year, besting the thrifty Swiss for a second straight year, according to an international survey.

Japanese per capita savings were $38,439 at the end of 1987, an increase of $11,136 from the previous year, according to a study released Monday by the International Savings Banks Institute.Switzerland, which had been the leader until 1986, last year recorded per-capita savings of $34,763, up $9,500 from the previous year.

The report cited the strong value of the yen and Swiss franc against the dollar as the main factors contributing to the high figures.

The 35-nation survey counted only bank savings.

Switzerland was followed by Belgium with $17,987, West Germany with $16,102 and Austria with $13,269.

The U.S. savings rate is $9,888, up from $9,529 in 1986.

The countries with the lowest per capita savings, the study said, were Niger, with $7; Ethiopia, with $18, and Senegal, with $69.