Productivity measures the efficiency with which production inputs, such as labour and capital, are being used in an economy to produce a given level of output, and is considered a key source of economic growth and competitiveness. One of the most widely used measures of productivity is labour productivity (LP). It reflects output per worker, here in terms of Gross Domestic Product (GDP) over persons employed. LP growth implies a higher level of output per unit of labour input. This can be achieved if more capital is used in production, i.e. capital deepening (CD), or through improved overall efficiency with which labour and capital are used together, i.e. higher multifactor productivity growth (MFP). Capital deepening reflects investment in physical and intangible capital (so-called knowledge-based capital), and is defined as the ratio of capital services per hour worked. Investment in information and communication technologies (ICT) that enables new technologies to enter the production process is thought to be especially productivity-enhancing. It is therefore singled out in the graph "Capital per hour worked" (see dropdown).