asked the Secretary of State for Energy what was the average output of coal per manshift in deep coal mines in the most recent annual period for which figures are available; and what were the comparable totals for the deep mining industry 5, 10, 15, 20 and 30 years previously, respectively.
Information relating to the average output of coal per manshift is recorded only from deep mines operated by the National Coal Board. For these mines the figures, including the latest information available for a 52-week period, are as follows:
| tonnes | ||
| 1949 | … | 1·20 |
| 1959 | … | 1·37 |
| 1964 | … | 1·75 |
| 1969 | … | 2·21 |
| 1974 | … | 2·18 |
| 52 weeks ended 8.12.79 | … | 2·24 |
The figures for 1949 and 1959 are not strictly comparable with the later years shown, as prior to 1960 the maximum daily hours of attendance underground were seven and a half hours per shift compared with seven and a quarter hours afterwards