ship                        builder          laid down           launched      commissioned
0         dolfijn       rotterdamse droogdok mij   30 december 1954        20 may 1959  16 december 1960
1         zeehond       rotterdamse droogdok mij   30 december 1954   20 february 1960     16 march 1961
2  potvis - class                 potvis - class     potvis - class     potvis - class    potvis - class
3          potvis  wilton - fijenoord , schiedam  17 september 1962    12 january 1965   2 november 1965
4          tonijn  wilton - fijenoord , schiedam    26 october 1962  14 june 1965 1965  24 february 1966

Table as JSON:
{"ship":{"0":"dolfijn","1":"zeehond","2":"potvis - class","3":"potvis","4":"tonijn"},"builder":{"0":"rotterdamse droogdok mij","1":"rotterdamse droogdok mij","2":"potvis - class","3":"wilton - fijenoord , schiedam","4":"wilton - fijenoord , schiedam"},"laid down":{"0":"30 december 1954","1":"30 december 1954","2":"potvis - class","3":"17 september 1962","4":"26 october 1962"},"launched":{"0":"20 may 1959","1":"20 february 1960","2":"potvis - class","3":"12 january 1965","4":"14 june 1965 1965"},"commissioned":{"0":"16 december 1960","1":"16 march 1961","2":"potvis - class","3":"2 november 1965","4":"24 february 1966"}}