Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Name | Date | Nation | Displacement | Speed | Number | Notes |
| --- | --- | --- | --- | --- | --- | --- |
| River-class frigates | 1942 | UK | 1,370 tons | 20 knots | 151 |  |
| Type A kaibōkan | 1943 | Japan | 870 tons | 19 knots | 18 |  |
| FMR-class | 1943 | US | 1,200 tons | 21 knots | 85 |  |
| GMT-class | 1943 | US | 1,140 tons | 21 knots | 72 |  |
| TE-class | 1943 | US | 1,400 tons | 23 knots | 102 |  |
| DET-class | 1943 | US | 1,240 tons | 21 knots | 72 |  |
| Tacoma-class frigate | 1943 | US | 1,430 tons | 20 knots | 96 |  |
| Type B kaibōkan | 1943 | Japan | 940 tons | 19 knots | 37 |  |
| Loch-class frigates | 1944 | UK | 1,435 tons | 20 knots | 30 |  |
| WGT-class | 1944 | US | 1,350 tons | 24 knots | 87 |  |
| TEV-class | 1944 | US | 1,450 tons | 24 knots | 22 |  |
| Bay-class frigates | 1945 | UK | 1,580 tons | 20 knots | 26 | anti-aircraft |
| Dealey-class | 1954 | US | 1,450 tons | 25 knots | 13 |  |
| Type E50 frigate | 1955 | France | 1,290 tons | 28 knots | 4 | fast |
| Type 14 frigate | 1955 | UK | 1,180 tons | 24 knots | 8 | anti-submarine |
| St. Laurent-class | 1955 | Canada | 2,263 tons | 28 knots | 7 | anti-submarine |
| Type B | 1956 | Japan | 1,070 tons | 25 knots | 2 | diesel |
| Type 12 frigate | 1956 | UK | 2,150 tons | 31 knots | 6 | anti-submarine |
| Type E52 frigate | 1956 | France | 1,295 tons | 28 knots | 14 | fast |
| Almirante Clemente-class light destroyer | 1956 | Venezuela | 1,300 tons | 32 knots | 6 | fast |
| Type 61 frigate | 1957 | UK | 2,170 tons | 24 knots | 4 | aircraft direction |
| Canopo-class frigate | 1957 | Italy | 1,807 tons | 26 knots | 4 |  |
| Type 41 frigate | 1957 | UK | 2,300 tons | 24 knots | 4 | anti-aircraft |
| Azopardo-class frigate | 1957 | Argentina | 1,160 tons | 20 knots | 2 |  |
| Restigouche-class | 1958 | Canada | 2,366 tons | 28 knots | 7 | anti-submarine |
| Claud Jones-class | 1959 | US | 1,450 tons | 22 knots | 4 |  |
| Type 12M frigate | 1960 | UK | 2,380 tons | 30 knots | 12 | anti-submarine |
| Köln-class frigate | 1961 | Germany | 2,100 tons | 30 knots | 6 | fast |
| River-class | 1961 | Australia | 2,100 tons | 30 knots | 6 |  |
| River-class | 1961 | Japan | 1,490 tons | 25 knots | 4 |  |
| Type 81 frigate | 1961 | UK | 2,300 tons | 28 knots | 7 | general purpose |
| Bergamini-class frigate | 1961 | Italy | 1,410 tons | 26 knots | 4 |  |
| Commandant Rivière-class frigate | 1962 | France | 1,750 tons | 25 knots | 13 | dual purpose |
| Mackenzie-class | 1962 | Canada | 2,366 tons | 28 knots | 4 | anti-submarine |
| Hvidbjørnen-class frigate | 1962 | Denmark | 1,345 tons | 18 knots | 4 | fishery protection |
| Type 12I frigate | 1963 | UK | 2,450 tons | 30 knots | 26 | general purpose |
| Bronstein-class | 1963 | US | 2,360 tons | 26 knots | 2 |  |
| Garcia-class | 1964 | US | 2,620 tons | 27 knots | 10 |  |
| Oslo-class frigate | 1966 | Norway | 1,450 tons | 25 knots | 5 |  |
| Brooke-class | 1966 | US | 2,640 tons | 27 knots | 6 | guided missile |
| Peder Skram-class frigate | 1966 | Denmark | 2,030 tons | 28 knots | 2 | fast |
| Van Speijk-class frigate | 1967 | Netherlands | 2,200 tons | 28 knots | 6 |  |
| Alpino-class frigate | 1968 | Italy | 2,000 tons | 28 knots | 2 |  |
| Alvand-class frigate | 1968 | Iran | 1,110 tons | 40 knots | 4 |  |
| Knox-class | 1969 | US | 3,011 tons | 27 knots | 46 |  |
| Chikugo-class | 1971 | Japan | 1,470 tons | 25 knots | 11 |  |
Question:
how many tons of displacement does type b have?
Answer:
940 tons