asked the Secretary of State for the Environment what was the total number of firms in the construction industry added to his Department's statistical register in each of the last ten years; and how many of the firms removed from the register in each year had been trading for less than two years, less than ten years and more than 10 years, respectively.

The number of firms in the construction industry added to the Department's statistical register in each of the last 10 years is as follows:

1962	4,851
1963	3,611
1964	3,359
1965	4,043
1966	4,887
1967	4,342
1968	3,035
1969	3,270
1970	3,403
1971	3,868

To extract information about the lengths of time firms had been on the Department's statistical register before they were removed from it would involve a disproportionate amount of time and effort, and even that information would not necessarily indicate the length of time firms had been trading.