Mr. Paul Hogan:

The Senator wanted to tease out a little more what we mean by the "mid-range" of population projections and scenarios. It is not just a demographic scenario but also a econometric scenario. It looks at the mid-term economic review and the prospects for the economy, and distributes population with regard to vote demographics, the econometric modelling and places around the country. Like any model or assessment, it makes assumptions but they are grounded in the likely reality. When calibrated against the Central Statistics Office, CSO, as a mid-range scenario for long-term population and labour force growth, it more or less correlates with the CSO's mid-range scenario, which is what would be described as the traditional, most likely scenario.

There are a couple of underlying aspects to that. First, the number of births and deaths in our population is below replacement levels. If there was zero net migration, our population would be slowly falling, and that is typical of developed economies. The birth rate needs to be approximately 2.1% for replacement, but we are at approximately 1.85% and slowly falling. We are dependent, therefore, on migration for population growth.

In general terms, approximately half of our migrants over a long period tend to be returning Irish people who have lived abroad or started their working careers abroad, while the other half tend to be from elsewhere in the EU, in general, or from the rest of the world. The capacity to accommodate people in the country, with the level of economic growth and employment we now have, is not endless. If it was to extend for a protracted period beyond the figures we are talking about, it is clear the capacity would not be there for employment, accommodation and so on for people.

There is an economic equilibrium or a limiting factor in that regard, and that is the sort of consideration that is taken into account when making assumptions for a model to make a projection into the future. The figure of 30,000, therefore, is considered to be in the upper range. We should bear in mind that, in projection terms, these are straight line figures. One presumes a figure of 20,000 or 30,000 every year for the next 20 years, but those sorts of patterns are not the reality. There will be fluctuations, where it may be lower in the short term, higher in the middle of the period and then lower again, as is the nature of our economic cycle. All of those things considered, it is a mid-range projection averaged out over the period, and that is how it works. In regard to the figure of 30,000, compared with what happened in the past, that figure was not exceeded for more than approximately six years during the previous boom, which we do not necessarily expect to be replicated, although it could be. When put into an average 20 year period, it works out at approximately 20,000. Based on the information we have, it is felt it is the most prudent way to go.

On infrastructure and infrastructural planning, part of the logic of the NPF is to try to identify where investment can be influenced and where people and employment can be influenced by decisions about employment and housing.

The Department of Finance and the Department of Public Expenditure and Reform have set a sustainable level of investment in infrastructure at approximately 3.5% of gross national product star, GNP*, which is our gross domestic product, GDP, equivalent. That is seen as sustainable to 2027. The national development plan, NDP, is based on that level of investment. It is higher than the European average which is approximately 3% of GDP. The objective of the NDP is to target that investment where it can be most effective and where it can deliver growth that will make a difference for the regions as much as for Dublin.