Further to the above, I've found the statistics you tried to present inactivity ones as, namely benefit claimants.
http://www.ippr.org/members/download.asp?f=/ecomm/files/britains_migrants.pdf&a=skip
Commissioned in 2007 for Dispatches on Channel 4.
Table 5.9 contains the unemployment claim rates (highest is 5%, somalians, bangladeshis etc, the lowest is poles and the USA, rounds down to zero.)
Table 5.10 contains income support claim rates, Those born in the UK come in at 15th on 4% of the population, there are a significant number of immigrants on both sides of the population. (For the avoidance of doubt, the report uses a definition of immigrant that involves people not born here, not based on race or skin colour for people who were born in the UK).
Table 5.11 Shows a similar picture for disability claims, with UK born sitting at 19th in the table.
Table 5.12 is child benefit, which is available to all and shows nothing really of interest.
Table 5.13 shows proportions living in social housing, again, UK born sit in the middle of the table (15th), with plenty of immigrants on either side.
There is some work done on ethnic group rather than country of birth around section 6, but it's more focused on education and employment than benefit claims.
Now, I'll just quote from the conclusion.
it is clear that on most criteria, most immigrant groups do better in
economic terms than the UK-born population. Overall, when we take into account the
relative size of the groups studied in this report, it would seem that the average immigrant has better economic characteristics than the average UK-born person.
Emphasis as per the report.
The study does also acknowledge
There are some immigrant communities who rank consistently lower on most indicators than the UK average. In
some cases, these relatively low-ranking communities are predominantly made up of people
who have come to the UK for non-economic reasons (for example, to join family members
who are already in the UK, or to seek asylum).
The bottom line is that it's far from clear cut that immigrants are not economically useful, some of them aren't, and indeed I'm not convinced (and this study did not look at it) that many of those working and not claiming benefit reach the break-even point where their presence provides a net economic benefit, when all factors are considered. I've said before and I'll repeat, for the avoidance of doubt, that I think the immigration system needs major reform, and that we should not be allowing in many of the people that we do. But let's at least do it on an honest evaluation of what's actually happening.