Among businesses, the share of total lobbying expenditures accounted for by the top 100 organizations is between 37% (2011) and 48% (1998); and the share of total personnel representing the top 100 organizations is between 35% (2008, 2009) and 47% (2000). For non-business organizations, the spending concentrated in the top tier organizations ranges between 31% (2008-2009) and 46% (1998), and the personnel concentration ranges between 48% (2008-2009) and 74% (1998). Though the concentration does decline somewhat over the 15-year period, one has to keep in mind that the overall lobbying expenditures more than double between 1998 and 2009. So the denominator is increasing significantly. That the concentration of activity in a small number of organizations relatively remains stable during this period of generally increasing expenditures is important.