Over 40 years ago the Economic and Social Research Institute produced the first estimates of the income levels of each of our counties.
The Central Statistics Office, which since 1991 has prepared these studies, has just published data for 2001, which makes it possible to see the progress made by each county during the Celtic Tiger years - and indeed, since 1960.
During the 41 years to 2001 the purchasing power of the average pre-tax income in the State has quintupled - an impressive measure of our long-term economic progress.
But this much-increased income now has to be shared amongst one-third more people than there were in 1960, and the proportions of our incomes that we save and that are absorbed by personal income taxes have also risen significantly during the past 40 years, leaving a lesser share of personal income for us to spend.
In 1960 most of the cost of the very limited public services and public investment were covered by excise duties and by rates on domestic property: only 5 per cent of what we earned was taken in income tax. The abolition of domestic rates on dwellings 25 years ago, combined with the much more extensive public services of today and the hugely increased volume of public investment required to update our grossly inadequate infrastructure, have raised the proportion of income absorbed by personal taxation to almost 20 per cent, in addition to which we also now pay VAT.
So the average volume of goods and services consumed per head of population today is not five times but rather 3½ times greater than in 1960, which is still a quite formidable rise in material living standards.
Has this increased prosperity been evenly spread throughout our State? Reasonably so: no part has had less than a four-fold increase in output and real incomes, and no area has secured more than a six-fold increase.
The biggest disparity has been between dynamic Sligo and sluggish Donegal. In 1960 incomes in Sligo were one-sixth lower than in Donegal. But, because incomes in Sligo rose faster than the national average, both in the first 33 years of this period, and also during the Celtic Tiger period, by the year 2001 they were one-fifth higher than in Donegal.
In general, however, the 33-year pre-Celtic Tiger period up to 1993 was marked by faster growth in what had traditionally been poorer western parts of the country with the result that counties such as Sligo, Leitrim, Longford, and Clare saw their income gaps vis-a-vis Dublin halved, whilst Galway, Roscommon and Cavan saw their income gaps with Dublin reduced by about one-third. Thus, to a much greater extent than was generally realised at the time, that was a period during which a greatly improved regional balance was achieved.
The Celtic Tiger led to a marked shift in this pattern. In this more recent period high-tech investments in the Dublin region - especially in Kildare - helped this more prosperous part of the State to hold its own vis-à-vis the other counties. In addition, because some of the workers in these industries and in supporting services were housed in nearby parts of Meath and Wicklow, and indeed south Louth, incomes were boosted in those counties also. Galway, Limerick and Sligo also benefited from this new industrial investment.
During both these periods, however, Waterford lost ground. The contrast between the economic performance of that county and city and the growth of incomes in the county and city of Galway is particularly striking.
Despite Galway's much larger rural hinterland, during the recent Tiger period it caught up with, and indeed in average income terms passed out, its geographically better-placed south-eastern rival - which back in 1960 had had an income level almost one-quarter higher than that of the capital of the west.
This failure of Waterford to cash in on its location as the city port nearest to the continental EU countries remains a puzzling feature of Irish economic geography. Neither does it seem to be explained simply by the different status of their higher education institutions - as some in that city seem to believe.
It is in the nature of things that the differences in income levels between various parts of the State require substantial transfers of resources between richer and poorer areas.
Despite Dublin city's areas of severe disadvantage, this well-off region as a whole does not require, nor does it receive, social transfers on the same scale as the rest of the State.
And, because of the higher average incomes there, this region naturally, and properly, contributes much more through taxation than any other county - an average of between €4,000 and €5,000 per head in 2001.
In fact, in this Dublin region these tax payments exceed by more than two-thirds the social transfers required to support less-well-off people there.
At the other end of the spectrum there are seven counties whose tax payments in 2001 did not even cover the social benefits paid out to their less-well-off inhabitants. This means they were unable to make any contribution whatever to the government of the country, to public services, or to public investment. These seven counties are Donegal, Leitrim, Mayo, Longford, and Kerry in the west, and Wexford and Carlow in the south-east. The absence of industry has always been a problem for Wexford, but I have to say that the Carlow situation comes as a something of a surprise to me.
All of the funds needed to finance the processes of government, the public services and public investment - what might be described as "general government" as distinct from social transfers - have to be provided by the remaining counties. These are the counties that contribute more in taxation than they receive in social transfers, although a small proportion of the taxes paid by these better-off counties also have to be used to make up the €220 million which the seven counties just mentioned need for social purposes over and above their tax payments.
It is not realised generally that of the €4 billion excess of tax revenue over social transfers that is required to contribute towards the cost of general government, (the great bulk of which derives from VAT and Corporation Tax), Dublin provides 55 per cent, the counties around Dublin contribute almost 20 per cent, and Cork provides almost 10 per cent.